Forearm Cuff V1

implemented unverified

Wave P2: the first wearable — a forearm cuff with a cylindrical payload snap-clip (flashlight / prop cylinder 20..30 mm) on top. ONE constant YZ section extruded along X (X = the forearm axis), printed on its profile: support-free by construction. The arm saddle is sized from the body_fit block (circumference + clearance), only LIGHTLY clips the limb (donning window measured against flesh diameter — retention belongs to the STRAPS through the two mouth-tip tabs), carries three recessed TPU pad lands and comfort fillets on every skin edge. The payload snap-C rides outside the ring, mouth away from the body (pipe-clip arc-retention physics — the first client of BUILDERS.md cylindrical_cradle). The outer shell is an exoskeleton_panel reserved for the bio skin (Bio-4M stage B canvas — next iteration).

Built from a real example — orbit to inspect.

Declaration example

A minimal product declaration for this archetype — exposed parameters at their defaults. Validate and build it with forge validate / forge build.

schema: product/v1
id: my_forearm_cuff
archetype: forearm_cuff_v1@1

params:
  arm_circumference: expr(body_circumference)
  cuff_l: expr(min(body_length * 0.35, 90))
  payload_d: 25mm

modifiers:
  - id: add_strap_slots
    target: strap_land_left

Parameters

parameter	type	default	range	role
`arm_circumference`forearm circumference at the cuff seat — defaults to the body_fit block; without body_fit this parameter honestly FAILs	`length`	`expr(body_circumference)`	`150mm … 450mm`	functional	exposed
`arm_clearance`radial air between skin and cuff (donning + comfort)	`length`	`expr(body_clearance)`	`2mm … 12mm`	functional
`cuff_l`cuff width along the forearm axis	`length`	`expr(min(body_length * 0.35, 90))`	`40mm … 120mm`	structural	exposed
`strap_w`strap width the tabs must host (add_strap_slots matches it)	`length`	`expr(body_strap_width)`	`15mm … 40mm`	assembly
`wall`ring wall between the arm cavity and the outer shell	`length`	`4mm`	`expr(2 * printer_min_wall) … 8mm`	structural
`arm_capture_deg`arm saddle coverage: below ~240 with a generous clearance the mouth exceeds the flesh diameter and form.arm_mouth_dons_ok honestly fails	`number`	`240`	`210 … 262`	functional
`land_angle`pad land positions, degrees each side of the saddle top	`number`	`45`	`25 … 60`	functional
`land_w`	`length`	`14mm`	`8mm … 20mm`	functional
`pad_recess`radial pocket depth for glued TPU/foam pads (outward)	`length`	`1.5mm`	`0.8mm … 2.5mm`	functional
`comfort_edge_r`minimum fillet on every skin-contact edge	`length`	`2mm`	`1.2mm … 4mm`	functional
`tab_t`strap tab thickness	`length`	`4mm`	`3mm … 6mm`	structural
`tab_len`strap tab reach beyond the mouth tip	`length`	`26mm`	`20mm … 40mm`	structural
`payload_d`payload cylinder diameter (flashlight body)	`length`	`25mm`	`20mm … 30mm`	functional	exposed
`payload_clearance`	`length`	`0.3mm`	`0.1mm … 0.8mm`	functional
`payload_arc_deg`payload snap coverage — arc retention, not lips	`number`	`240`	`210 … 268`	functional
`clip_wall`	`length`	`3mm`	`2.4mm … 5mm`	structural
`neck_drop`bridge between the ring crown and the payload clip	`length`	`4mm`	`2mm … 10mm`	structural