# Building Blocks & Construction

Building toys are not one category but four: studded bricks, magnetic tiles, wooden stacking blocks, and rod-and-connector engineering sets. Each has its own connection mechanism, and that mechanism, not piece count or price, decides whether a build locks rigid, balances free, or snaps together.

## How it works

A construction toy's pieces hold together one of five ways: studs pressed into tubes (plastic bricks), magnetic poles (tiles and rods), notches cut to interlock (log sets), plain gravity and friction (plank-stacking sets), or mechanical fasteners like nuts and bolts (metal engineering sets). The mechanism sets the trade-off: studs and notches give a rigid, forgiving hold that survives being carried across a room; magnets and gravity-stacked planks give near-zero resistance so building and balance become the skill, but a bumped table collapses the whole structure. Piece scale is tied to the same mechanism: brands double a piece's size (Duplo vs. standard Lego) specifically to keep it too large to be a choking hazard for children under three.

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Construction system
    stud_bricks : ask Brick plastic, Brick scale, Included element types : skip Magnet type and mounting, Tile/rod shape system, Piece shell material, Wood species, Wood block connection, Wood finish, Connector material, Tool requirement, Motion and mechanism
    magnetic : ask Magnet type and mounting, Tile/rod shape system, Piece shell material : skip Brick plastic, Brick scale, Included element types, Wood species, Wood block connection, Wood finish, Connector material, Tool requirement, Motion and mechanism
    wood_stacking : ask Wood species, Wood block connection, Wood finish : skip Brick plastic, Brick scale, Included element types, Magnet type and mounting, Tile/rod shape system, Piece shell material, Connector material, Tool requirement, Motion and mechanism
    engineering_sets : ask Connector material, Tool requirement, Motion and mechanism : skip Brick plastic, Brick scale, Included element types, Magnet type and mounting, Tile/rod shape system, Piece shell material, Wood species, Wood block connection, Wood finish
  section 2 · Builder age
    toddler_18mo_3y : skip Tool requirement, Motion and mechanism
  section 3 · Open-ended or instruction-led
    Build whatever comes to mind, or follow step-by-step instructions to a model?
```

1. **Construction system.** Studded plastic bricks, magnetic tiles, wooden blocks, or gears-and-rods engineering sets?
   Each system's defining spec lives elsewhere: bricks in plastic and stud scale, tiles in magnet type, wood in species and notch, engineering sets in connector and fastener.
   If stud_bricks: ask Brick plastic, Brick scale, Included element types; skip Magnet type and mounting, Tile/rod shape system, Piece shell material, Wood species, Wood block connection, Wood finish, Connector material, Tool requirement, Motion and mechanism.
   If magnetic: ask Magnet type and mounting, Tile/rod shape system, Piece shell material; skip Brick plastic, Brick scale, Included element types, Wood species, Wood block connection, Wood finish, Connector material, Tool requirement, Motion and mechanism.
   If wood_stacking: ask Wood species, Wood block connection, Wood finish; skip Brick plastic, Brick scale, Included element types, Magnet type and mounting, Tile/rod shape system, Piece shell material, Connector material, Tool requirement, Motion and mechanism.
   If engineering_sets: ask Connector material, Tool requirement, Motion and mechanism; skip Brick plastic, Brick scale, Included element types, Magnet type and mounting, Tile/rod shape system, Piece shell material, Wood species, Wood block connection, Wood finish.
   Skip if already known: a query naming a brand (Lego, Magna-Tiles, Lincoln Logs, K'Nex, Meccano) that implies the system, an earlier answer naming studs, magnets, wood, or gears/rods.

2. **Builder age.** Toddler, preschooler, grade-schooler, or teen/adult builder?
   Age sets the piece scale and fastener risk the other facets have to respect: toddlers need Duplo-scale pieces and no loose small parts; teens can handle nut-and-bolt engineering sets and motors.
   If toddler_18mo_3y: skip Tool requirement, Motion and mechanism.
   Skip if already known: an earlier answer naming a specific child age or 'for myself'/'adult'.

3. **Open-ended or instruction-led.** Build whatever comes to mind, or follow step-by-step instructions to a model?
   Open-ended sets are judged on piece versatility and shape variety; instruction-led kits are judged on how close the final model matches the box and whether it survives disassembly and rebuilding.
   Skip if already known: an earlier answer naming 'freeform', 'creative', 'kit', or a specific model to build.

## What to surface

### Construction system

Which of the four physical systems the pieces use to hold together: studded plastic bricks, magnetic tiles/rods, wooden stacking blocks, or rod-and-connector/nut-and-bolt engineering sets. It is the single fork that determines everything else worth asking: a brick's material and stud scale, a tile's magnet type, a wood block's species and notch, or an engineering set's connector and fastener. Asking this first avoids asking about stud pitch on a magnetic set or magnet strength on a wooden one. [2] [1]

Values: stud_bricks, magnetic, wood_stacking, engineering_sets.
Question to ask: Studded plastic bricks, magnetic tiles, wooden blocks, or gears-and-rods engineering sets?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost low. Look for it as: Derive from the product title and category breadcrumb ('building bricks', 'magnetic tiles', 'wooden blocks', 'STEM building set').
Title and category keyword match covers nearly every listing; ambiguous titles default to stud_bricks, the largest segment.

### Builder age

The intended builder's age band: toddler (18mo-3y), preschool (3-6y), grade-school (6-12y), or teen/adult. Age is tied directly to piece scale and fastener risk: brands double piece size for toddlers specifically so it cannot pass a small-parts choking test, and nut-and-bolt or motorized sets assume the fine motor skills and supervision of an older child. [8] [6]

Values: toddler_18mo_3y, preschool_3_6y, grade_school_6_12y, teen_adult_12y_plus.
Question to ask: Toddler, preschooler, grade-schooler, or teen/adult builder?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: Usually a printed age range on the box front, often duplicated in the listing title or a dedicated age-range field.
Most listings carry an explicit minimum age; when absent, default by piece scale (large pieces imply toddler-safe, small/metal implies 6+).

### Open-ended or instruction-led

Whether the set is marketed for freeform, undirected building or for assembling a specific model from included step-by-step instructions. It changes what 'good' looks like: an open-ended bucket is judged on how many different things the piece shapes can become, while an instruction-led kit is judged on fidelity to the pictured model and whether the pieces survive being taken apart and rebuilt as something else. [8] [2]

Values: open_ended_building, instruction_model_kit.
Question to ask: Build whatever comes to mind, or follow step-by-step instructions to a model?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: Often implied by set naming ('Classic Bucket', 'Creative Box' vs. a named model like 'Fire Truck' or 'Castle') rather than a stated field.
Keyword-match 'classic', 'bucket', 'creative' to open-ended; a named vehicle/building/model title with a piece count implies instruction-led.

### Set size

How many pieces the set ships with, bucketed into starter (under 100), standard (100-500), large (500-1500), or mega (1500+). Piece count tracks structural ambition and build time more reliably than price: a starter set builds one small model in minutes, while a mega set supports room-scale structures or several simultaneous builds, and most ecosystems let you combine sets to move up a band. [8]

Values: starter_under_100, standard_100_500, large_500_1500, mega_1500_plus.
Question to ask: Roughly how many pieces — a handful, a few hundred, or thousands?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: Piece count is almost always a stated field or in the title ('863 pcs', '100-Piece Set').
Band cutoffs (100/500/1500) are an editorial convention, not a cited industry standard; parse the piece count from the title and bucket by nearest round threshold.
Chart: position on a build-scale axis by piece count band.

### Brick scale

Whether the bricks are standard scale or large toddler scale (roughly double the linear dimensions of a standard brick on every axis). Large-scale bricks exist specifically to be too big to fit a small-parts choking-test cylinder, so they are the only scale appropriate for children under 3; standard-scale bricks pack far more detail per model but are a choking hazard at that age. [1] [6]

Values: standard_scale, large_toddler_scale.
Question to ask: Regular-size bricks, or the extra-large toddler kind?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Usually explicit in the title ('Duplo', 'jumbo blocks', 'toddler-size bricks') or implied by a stated age under 3.
Keyword-match 'duplo', 'jumbo', 'big building blocks', or toddler age claims to large_toddler_scale; default standard_scale otherwise.
Chart: position on a piece-size axis.

### Small-parts class

Whether the set's pieces are large enough to pass as safe for children under 3, or carry a small-parts choking warning restricting it to 3-plus. This is a governed safety classification, not a style choice: US and EU toy-safety testing requires a choking-hazard warning on any set whose pieces fit a small-parts test cylinder, and manufacturers who want to sell to toddlers (e.g. Duplo-scale brick lines) deliberately oversize pieces to avoid that classification entirely. [6] [1]

Values: toddler_safe_oversized, small_parts_warning_3plus.
Question to ask: Does it warn about choking, or say it's safe under 3?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: A 'WARNING: CHOKING HAZARD - small parts' line is legally required on US listings for sets that need it; its absence plus a 'ages 1.5+' or 'toddler' claim implies oversized pieces.
Scan the listing's safety/warning text field for 'choking hazard' or 'small parts'; default to small_parts_warning_3plus when the stated minimum age is 3 or higher.

### Tile/rod shape system

Whether the pieces are flat geometric panels (squares, triangles, etc.) meant to be built into walls and enclosures, or rods and connecting balls/hubs meant to be built into 3D frames. Flat panel systems build enclosed, room-like structures (houses, castles) and lie flat for toddlers to start with; rod-and-hub systems build open 3D frameworks (towers, bridges) and reward spatial planning over surface area. [7] [2]

Values: flat_geometric_panels, rods_and_connecting_hubs.
Question to ask: Flat shapes that build walls, or rods and balls that build frames?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Visible in the product photo; title usually says 'magnetic tiles' vs 'magnetic building rods/sticks'.
Keyword-match 'tiles' to flat_geometric_panels and 'rods'/'sticks'/'balls' to rods_and_connecting_hubs.

### Wood block connection

Whether wooden pieces hold together purely by gravity and friction (plain stacking blocks and thin balance planks) or by cut notches that interlock (log-cabin style sets). No-connection stacking makes balance and structural planning the entire challenge, since any piece can be lifted straight off; notched sets lock at the joint, so they build sturdier, more permanent models like cabins but are less forgiving to disassemble and resort. [2] [5]

Values: no_connection_gravity_stack, notched_interlock.
Question to ask: Do pieces just stack, or notch together like a log cabin?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Visible in product photos; log-style sets show visible notches and round or half-round pieces.
Keyword-match 'log', 'notch', or 'cabin' to notched_interlock; default plain rectangular block/plank sets to no_connection_gravity_stack.

### Connector material

Whether the structural pieces are molded plastic (rods and connector hubs) or metal strips/plates/girders joined with separate fasteners. Plastic rod systems are lighter, color-coded by length, and snap together by hand; metal strip systems are heavier, carry real mechanical load, and were originally designed to teach actual engineering principles like levers and gearing rather than just shape-building. [3] [4]

Values: plastic_rods_and_hubs, metal_strips_and_girders, mixed_metal_and_plastic.
Question to ask: Plastic rods and connectors, or metal strips and girders?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Visible in the product photo; titles usually say 'building rods' (plastic) or name a metal-strip brand/style.
Keyword-match 'metal', 'steel', 'girder' to metal_strips_and_girders; default plastic_rods_and_hubs otherwise.

### Motion and mechanism

Whether the set builds only static structures, or includes gears/wheels for manual motion, or a motor for powered motion. Adding gears turns a static shape into something that transmits motion (a crank turning a wheel); adding a motor turns it into a working machine, which is the whole appeal of the 'engineering set' category over a plain building-brick set, and is usually the single most expensive add-on in the line. [3] [4]

Values: static_only, manual_gears_and_wheels, motorized.
Question to ask: Just structures, gears you turn by hand, or a motor?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Usually explicit in the title or bullets ('motorized', 'with motor', 'gear set').
Keyword-match 'motor' to motorized, 'gear'/'crank'/'wheel' to manual_gears_and_wheels, default static_only otherwise.

### Ecosystem compatibility

Whether a piece only connects within its own brand's line, connects with most sets claiming the same standard (e.g. stud pitch or tile base size), or is a one-off proprietary shape. Buyers who already own pieces care most about whether a new set extends their existing collection or sits apart from it; brick and tile ecosystems compete partly on how openly they interconnect with rival brands' pieces of the same nominal standard. [1] [7]

Values: brand_proprietary, cross_brand_compatible, universal_open_standard.
Question to ask: Do you need it to connect with pieces you already own?

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Rarely a stated field; look for 'compatible with' claims or 'fits standard bricks/tiles' language in the description.
Default to brand_proprietary unless the listing explicitly claims compatibility with a named rival brand or standard.

### Brick plastic

What the bricks themselves are molded from: ABS (the industry standard), a softer PVC/ABS blend typical of budget clone brands, or bioplastic. ABS holds an injection-mold tolerance tight enough (down to about 10-20 micrometres) to give bricks their 'clutch power' — a firm press-fit that still pulls apart by hand; softer or looser-tolerance plastics feel mushy or fall apart under their own weight once a structure gets tall. [1]

Values: abs, pvc_blend, bioplastic, unspecified.
Question to ask: Does the listing say ABS plastic, or just 'plastic'?

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Premium brick brands state 'ABS' in materials; budget/clone brands often just say 'plastic' or 'ABS/PVC'.
Default to ABS for recognized brick brands and to pvc_blend/unspecified for unbranded or very low-priced sets, since ABS costs more to mold.
Chart: position on a clutch-power axis, ABS highest.

### Included element types

Whether the set contains only basic rectangular bricks, or also plates, slopes, wheels/axles, hinges, or figures. A basic-brick-only set can only build blocky, right-angled shapes; sets that add plates, slopes, wheels and hinges unlock curves, vehicles, and moving parts, which is what lets a builder go beyond towers and walls. [1]

Values: basic_bricks_only, bricks_plus_plates_and_slopes, bricks_plus_mechanical_elements, bricks_plus_figures.
Question to ask: Just blocks, or does it also have wheels, slopes, or little figures?

Used as: filter, shown on the card. Data: on the listing, backfill cost medium. Look for it as: Usually visible in the product photo or an 'includes' bullet list naming part types.
Scan bullet/description text for 'wheels', 'axles', 'slopes', 'minifigure', 'hinge'; default to basic_bricks_only when none appear.

### Wood species

The wood the blocks are milled from: hard maple (the original and most durable), birch or beech (mid-tier), or rubberwood/pine (budget). Species sets durability and price together: maple resists chipping and rounding at edges through decades of institutional use (classrooms), while softer rubberwood or pine dents and splinters sooner but costs noticeably less, which is why preschools and home buyers land on different tiers. [5]

Values: hard_maple, birch_or_beech, rubberwood_or_pine, mdf_or_composite, unspecified.
Question to ask: Does the listing name a wood type, like maple or rubberwood?

Used as: filter, shown on the card. Data: needs research, backfill cost high. Look for it as: Usually in the materials bullet or title for branded wooden block sets; unbranded sets often just say 'natural wood'.
Keyword-match the named species; default unspecified (treat as the cheaper tier) when only 'wood' is stated with no species.
Chart: position on a durability/price axis, maple highest.

### Wood finish

Whether the blocks are left raw/unfinished, sealed with a clear natural finish, or painted/lacquered in colors. Raw or clear-sealed wood keeps more grip between stacked pieces, which some builders prefer for stability, while painted/lacquered surfaces are smoother and glossier, which some find slicker to stack but easier to wipe clean and color-sort by. [5]

Values: raw_unfinished, clear_natural_finish, painted_or_lacquered.
Question to ask: Natural wood color, or painted in bright colors?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Visible in the product photo; titles often say 'natural' or 'rainbow'/'colored'.
Keyword/photo match for color presence; default clear_natural_finish for plain wood-tone photos.

### Tool requirement

Whether pieces snap together by hand or require a separate tool (screwdriver and wrench/spanner) to tighten nuts and bolts. Tool-free snap-fit systems can be built and rebuilt quickly by younger or impatient builders; nut-and-bolt systems take longer per joint but produce models that can bear real mechanical load and hold a pose, which is the entire point of a metal engineering set. [4]

Values: tool_free_snap_fit, requires_screwdriver_and_wrench.
Question to ask: Does it snap together by hand, or need a screwdriver and wrench?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Rod/connector sets are tool_free_snap_fit; metal strip-and-girder sets almost always include or require a small screwdriver and spanner.
Infer from connector_material: metal_strips_and_girders implies requires_screwdriver_and_wrench, plastic_rods_and_hubs implies tool_free_snap_fit.

### Water/bath tolerance

Whether the pieces are rated dishwasher-safe, tolerate splashing or bath/pool play, or must stay fully dry because of unsealed magnets or hollow cavities inside. Brands differ sharply here: some pieces are dishwasher-safe or bath-toy rated, others carry an explicit never-submerge warning, since unsealed magnets or hollow cavities can trap water and corrode internally. [7] [8]

Values: dry_use_only, bath_and_splash_tolerant, dishwasher_safe.
Question to ask: Does it need to survive water play, or stay dry?

Used as: filter, shown on the card. Data: needs research, backfill cost high. Look for it as: Rarely a standalone field; found in brand FAQ/care pages ('not waterproof', 'dishwasher-safe') rather than marketplace listings.
Default to dry_use_only when no water-care language appears; explicit 'submersible'/'dishwasher-safe'/'tub-safe' claims override to the stated tier.

### Magnet type and mounting

Whether the magnets are embedded and sealed inside each solid piece (ferrite/ceramic, used in flat building tiles) or loose, small, and separable rare-earth magnets. This is a governed safety line, not a performance spec: loose small high-powered (rare-earth) magnets that can be swallowed in pairs have caused serious intestinal injury and at least one death, leading to a major recall, while magnets sealed inside a solid tile piece carry no equivalent ingestion risk even though the tile itself could still be swallowed whole. [6] [7]

Values: embedded_ferrite_sealed, loose_rare_earth_separable.
Question to ask: Are the magnets sealed inside solid pieces, or small loose balls/discs?

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Flat geometric tile sets are almost always embedded_ferrite_sealed; loose small magnetic balls/discs are sold as 'magnetic building spheres' or similar and should carry an age-13+ or supervision warning.
Default flat tile/panel shapes to embedded_ferrite_sealed; default separately-packaged ball/pellet magnets to loose_rare_earth_separable.

### Piece shell material

The plastic the magnetic piece's outer shell is molded from, typically MABS (a methyl-methacrylate ABS blend chosen for clarity and toughness) or plain ABS/polycarbonate. Shell plastic decides how clear and scratch-resistant the translucent colors stay over years of play and whether the piece yellows or clouds; it does not affect magnet strength. [7]

Values: mabs, abs, polycarbonate, unspecified.
Question to ask: Does the brand page name the shell plastic?

Used as: shown on the card. Data: needs research, backfill cost high. Look for it as: Stated on brand pages more often than on marketplace listings; 'food-grade MABS' is common premium-brand language.
Rarely stated on third-party listings; default to unspecified unless the brand page is known.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Price per piece | `listed_price / piece_count` | The standard way builders compare a small premium set against a large bargain set without being fooled by the sticker price alone. [8] |

## What you give up

- Loose small rare-earth magnets grip far harder than the ferrite magnets sealed inside flat building tiles, which is why they build more ambitious 3D shapes, but that same loose, swallowable form is exactly what triggered a major recall after injuries and a death; sealed-tile systems give up some holding strength in exchange for having no equivalent ingestion risk. [6] [7] Board branch: "Stronger magnetic hold, more ingestion risk".
- A stud or notch holds a joint through a bump or a shoulder, letting a model survive being carried around; a gravity-stacked plank or block has no such lock, so the entire skill is distributing weight so the structure does not tip, and the reward is a more demanding, physics-first kind of building. [2] Board branch: "More rigid holds, less balance challenge".

## How to draw it

**Structural rigidity axis** (scale, shows Wood block connection, Magnet type and mounting). Where a system's joints sit from rigid (studs, notches, nut-and-bolt) to loose (gravity-stacked planks, magnetic poles), showing how forgiving a build is to bumps versus how much balance skill it rewards. This is a proposal, nobody draws it this way yet. [2]

## Words you will meet

- **ABS plastic**. Acrylonitrile butadiene styrene, the rigid plastic most name-brand bricks are molded from; it holds a tight mold tolerance so studs grip firmly but still pull apart by hand.
- **Clutch power**. The firm, repeatable grip between a stud and the tube under the brick above it, which is what lets a tall model hold together without glue.
- **Stud**. The small round bump on top of a brick that presses into the hollow tube underneath the brick stacked above it.
- **Ferrite magnet**. A ceramic magnet that is weaker than rare-earth types but cheap and stable, typically sealed permanently inside a solid tile piece.
- **Rare-earth magnet**. A very strong magnet (often neodymium) small enough to be sold loose as a separate piece, which is also what makes a swallowed pair dangerous.
- **MABS plastic**. A methyl-methacrylate/ABS blend chosen for magnetic tile shells because it stays clear and glossy rather than clouding over time.
- **Notched**. Cut with a groove or half-round channel so one piece seats into another and locks sideways, the way real log cabins are built.
- **Gravity stacking**. Holding pieces up with nothing but their own weight and friction against the piece below, with no interlocking feature at all.
- **Unit block**. The standard wooden block size (5.5 x 2.75 x 1.375 inches, a 1:2:4 ratio) that lets any block combine evenly with a double or quadruple-length piece.
- **BSW thread**. British Standard Whitworth, the thread pattern Meccano's nuts and bolts use, which is why true Meccano fasteners don't interchange with ordinary hardware-store screws.
- **Strut-and-node system**. A building system made of rods (struts) that plug into connector hubs (nodes), used by rod-and-connector engineering sets to build open 3D frames.
- **Choking hazard cylinder test**. The standard lab test (a small cylinder sized to a child's throat) that decides whether a toy's pieces are legally small enough to require a choking-hazard warning for children under 3.
- **Open-ended play**. Building without a target picture or instructions, where the pieces themselves set the limit rather than a model to match.
- **Minifigure**. A small posable human figure scaled to fit brick-built scenes, included in many bricks-plus-figures sets.
- **Stud pitch**. The fixed center-to-center spacing between studs on a brick's top; two brands only interlock if they share the same pitch.
- **Polycarbonate**. A tough, impact-resistant clear plastic sometimes used for tile shells instead of MABS; stronger, but more prone to yellowing over time.
- **MDF**. Medium-density fiberboard, a pressed wood-fiber composite sometimes sold as 'wood' blocks instead of solid maple, birch, or rubberwood.

## Where we made a call

- Lego's injection molds hold a tolerance of about 10 to 20 micrometres, which is what gives bricks their firm but removable stud grip. (confidence medium). Single-sourced to the Lego Wikipedia article's manufacturing section; a second independent engineering source was not reached this run. [1]
- Meccano's standard 1/2-inch hole pitch and 5/32in BSW fastener thread are what keep decades of Meccano parts interchangeable with each other. (confidence medium). Single-sourced to the Meccano Wikipedia article; a second independent spec source (e.g. a collector reference) was not reached this run. [4]
- US toy-safety choking and lead rules sit under CPSIA (which adopts ASTM F963); the EU equivalent is EN 71. (confidence high). CPSIA (2008) is the regulator standard choking_hazard_class and magnet_type rest on; Magna-Tiles' FAQ states CPSIA compliance directly, and EN 71 is the EU parallel. [6] [7]

## References

1. [Lego](https://en.wikipedia.org/wiki/Lego) (primer). Supports: Bricks are molded from ABS plastic with mold tolerances as small as 10-20 micrometres; Duplo bricks measure double the width, height and depth of standard bricks and target younger children.
2. [Construction set](https://en.wikipedia.org/wiki/Construction_set) (primer). Supports: Construction sets are categorized by connection method: studs, notches, no-connection/gravity stacking, struts-and-nodes, panels-and-screws, and magnets; No-connection wood systems include toy blocks, Anchor Stone Blocks, Kapla and unit bricks.
3. [K'Nex](https://en.wikipedia.org/wiki/K%27Nex) (primer). Supports: K'Nex is a rod-and-connector system of plastic rods, connectors, gears and wheels for ages 5-12.
4. [Meccano](https://en.wikipedia.org/wiki/Meccano) (primer). Supports: Meccano uses metal strips, plates and girders joined by nuts and bolts at a standard 1/2in hole pitch; The only tools required to assemble Meccano models are a screwdriver and spanners.
5. [Unit block](https://en.wikipedia.org/wiki/Unit_block) (primer). Supports: A unit block is 5.5 x 2.75 x 1.375 inches, a 1:2:4 ratio, with double and quadruple-length pieces; Maple blocks cost more than birch or beech, which cost more than rubberwood.
6. [Toy safety](https://en.wikipedia.org/wiki/Toy_safety) (regulator). Supports: US choking-hazard warning labels apply to toys with small parts aimed at children under three; The Magnetix construction toy was recalled after injuries and a fatality when its magnets came loose and were swallowed; The CPSIA (2008) adopts ASTM F963 toy-safety standards; EN 71 is the EU equivalent.
7. [Magna-Tiles FAQ](https://www.magnatiles.com/pages/faq) (spec sheet). Supports: Magna-Tiles pieces are made of food-grade MABS plastic and use embedded high-quality ceramic (ferrite) magnets; All Magna-Tiles pieces share a 3-inch base measurement and are fully compatible with one another; Magna-Tiles states it is fully CPSIA compliant, including lead and materials regulations; Magna-Tiles are not waterproof and should never be submerged, held under running water, or used in pools or bathtubs.
8. [Best Building Toys for Kids](https://www.goodhousekeeping.com/childrens-products/toy-reviews/g28568775/best-building-toys-for-kids/) (specialist review). Supports: Stated age ranges vary by brand/line: K'Nex beginner sets from 3+, standard K'Nex 5+, Magna-Tiles 4+, Lincoln Logs 3+; Building toys are compared on open-ended free play versus following step-by-step instructions; Clixo magnetic pieces are described as dishwasher-safe and travel-friendly.