Scope: tools for mechanically curling/shaping natural upper eyelashes and their direct companions — manual spring curlers, heated/electric curlers, replacement cushion pads sold on their own, and lash combs/separators used alongside a curler. Excludes false lashes, lash glue, mascara, lash serums, and salon lash-lift/extension services (own leaves or out of taxonomy).

Seed:
1. The eyelash-curlers equivalent of the treadwear-grade example is the curve angle (38°/60°) molded into shape-specific curlers: a number on the spec sheet that only compares reliably within one brand's naming, since "38°" on one brand isn't measured the same way as another's "almond-fit" claim.
2. An industrial designer would notice first that brands sell the *same* frame in two or three curve variants (narrow vs wide) rather than one "one size fits all" curve, and that the pad is a wear part engineered to be swapped on a cycle the frame is not — the real design decision is which part is disposable.

Sources:
[wikipedia_eyelash_curler] https://en.wikipedia.org/wiki/Eyelash_curler — mechanism, heated-vs-manual, safety risks — fetched excerpt
[tweezerman_classic] https://www.tweezerman.com/products/classic-lash-curler — silicone pad, 3 pads included, 3-month/1-year replacement, lower-lash caution — fetched excerpt
[tweezerman_almond_deepset] https://www.tweezerman.com/products/curler-for-almond-and-deep-set-eyes — 38° angle claim — fetched excerpt
[tweezerman_round_prominent] https://www.tweezerman.com/products/curler-for-round-and-prominent-eyes — 60° angle, wide opening — fetched excerpt
[tweezerman_promaster] https://www.tweezerman.com/products/pro-master-lash-curler — 38°, double body handle — fetched excerpt
[tweezerman_procurl] https://www.tweezerman.com/products/procurl — 60°, doubled body — fetched excerpt
[tweezerman_folding_ilashcomb] https://www.tweezerman.com/products/folding-ilashcomb-black — gold-plated metal tines, wet-mascara use — fetched excerpt
[tweezerman_lash_guard_comb] https://www.tweezerman.com/products/lash-gaurd-and-comb — transparent plastic comb, wet-mascara use — fetched excerpt
[kevynaucoin_eyelash_curler] https://kevynaucoinbeauty.com/products/eyelash-curler — universal wide curve, stainless steel, red silicone pad for placement contrast — fetched excerpt
[elle_best_eyelash_curlers] https://www.elle.com/beauty/makeup-skin-care/g29120862/best-eyelash-curlers/ — pad/clamp/eye-fit criteria, press-count technique, curve-vs-root nuance, grip — fetched excerpt
[fda_eye_cosmetic_safety] https://www.fda.gov/cosmetics/cosmetic-products/eye-cosmetic-safety — confirms no device-specific regulation of curlers — fetched excerpt

Branches:
tool_type → eyelash_curler/refill_pad/lash_comb_separator: each has a disjoint facet set (curve+mechanism vs fit+material vs tine+curve-match), per tweezerman_classic and tweezerman_lash_guard_comb showing non-overlapping spec sheets.
curler_mechanism → heated_electric makes hinge_design irrelevant: heated curlers in the sources are single-unit wand designs, not double-hinge levers (wikipedia_eyelash_curler).
eye_shape_curve → wide_open_curve asks opening_width: the round/prominent model explicitly pairs its wide curve with an extra-wide opening claim (tweezerman_round_prominent).

Noise (spec-sheet rows seen but not made facets):
- Handle color/finish (rose gold, neon pink, onyx) — cosmetic only, no functional difference; generic test fails.
- Price — excluded per rule (never a facet).
- "Award winner" badges (e.g. Allure Best of Beauty on lash guard & comb) — marketing, not a buyer-judged spec.
- Curl-hold duration in hours/days for heated curlers — no brand page with a measured number was reachable this run (Panasonic/retail pages blocked or 403/404); left out rather than invented, flagged in judgements instead.
- Heated curler battery type/warm-up time — same reason; no sourced number, so curler_mechanism stays categorical with no numeric sub-facet.
- No safety/test standard governs eyelash curlers as a device; FDA's eye-cosmetic guidance addresses applicators generally but does not name or regulate curlers specifically (fda_eye_cosmetic_safety) — confirmed absence rather than omitted.

Corrections (2026-10-26):
- eye_shape_curve split now asks opening_width on both narrow_closed_curve and wide_open_curve; tweezerman_promaster (38°, almond curve) ships an extra-wide opening while the base almond model ships a narrow one, so opening width is not gated by curve angle.
- Added numeric facet curve_angle_degrees (38° almond/deep-set, 60° round/prominent), each backed by two Tweezerman sources, instead of leaving the degree rating as free text.
- Dropped invented min/max bounds on pad_replacement_interval_months and pads_included_count; kept only the sourced typical values.
- curler_mechanism's heated_electric → hinge_design irrelevance is re-sourced to glam_heated_eyelash_curlers ("without scissor-like handles"), since the fetched wikipedia_eyelash_curler text never described heated curlers' physical shape.
- Dropped the comb_curve_match facet: tweezerman_classic has no comb content and neither fetched comb page (tweezerman_folding_ilashcomb, tweezerman_lash_guard_comb) names a curve-matched, eye-shape comb; no real curved_to_eye_shape example exists.
- pad_fit_compatibility gained a third value, no_refills_sold, sourced to kevynaucoin_eyelash_curler's own Q&A ("We do not sell replacement pads"), the bigger risk the brand-specific/universal split missed.
- Added vocabulary entries for almond, deep-set, round, prominent, and wide-set, the eye-shape terms driving the primary cold-start question.
- Added facet lash_length_compatibility (Elle's fourth fit axis), sourced to elle_best_eyelash_curlers and a tweezerman_lash_guard_comb customer review about very long lashes.
- Rejected: the checker's "Tweezerman reviewer" refill-unavailability quote could not be re-found in any fetched page this run, so only the confirmed Kevyn Aucoin Q&A backs the no_refills_sold value.