CAD Files for 3D Printing

Job Description: Please start your proposal with the word "KINETIC" so I know you have thoroughly read the brief and are an authentic applicant rather than an automated bot. Proposals omitting this word will be declined immediately. We are developing a professional-grade, door-anchored musculoskeletal mobility and spinal mobilisation station. The industrial design, mechanical architecture, and clinical dimensions are completely defined. However we need someone who will vet the physics, challenge the kinematics, and validate the ergonomics. We need an expert mechanical CAD engineer to model the complete parametric 3D CAD master assembly for functional prototyping and production. Production Roadmap: Immediate: 1x Functional Proof-of-Concept unit (SLS 3D Printing in PA12 Nylon). Phase 2: 50x Validation / Soft-Launch units (SLS PA12 Nylon + off-the-shelf COTS hardware). Phase 3: 1,000x Mass Production units (Tooling-ready injection molding; parts must already incorporate proper wall thicknesses, ribbing, and draft angles). Scope of Work & Sub-Assemblies: Carriage Housing & Outrigger Base: External envelope: 90 mm wide x 160 mm tall outrigger footprint (engineered to prevent lateral tipping under unilateral loads). Internal vertical strap passage: 52 mm wide x 2.4 mm deep channel with 3.5 mm flared entry/exit radii to ensure frictionless gliding over 50 mm seatbelt webbing. Recesses on the rear face for snap-in/press-fit low-friction UHMW glider strips to protect door timber. Internal Brake Kinematics & Transverse Rocker: Ergonomic twin side-pinch paddles actuating an internal transverse rocker lever. The rocker retracts a floating, high-friction brake shoe by 2.5 mm to 3.0 mm when squeezed. Twin stainless steel compression springs providing a positive fail-safe lock capable of resisting vertical shear under human bodyweight (~800 N slip resistance). Modular Attachment Interface (Indexed Lego-Style Friction Fit): Carriage Face: Central 40 mm quarter-turn female bayonet ring with an integrated 16 mm female square socket. Dual-Carrier Adapter Bar: Rear 40 mm male bayonet lug; front features two female 16 mm square sockets spaced 45.0 mm center-to-center. Modular Eccentric Pyramids (Identical Mold/Part): Base: 16 mm male square plug with retention detent for an indexed friction-fit. Apex: Blunted dome (radius of 10 mm or greater fillet) radially offset by 7.5 mm from the square plug centerline. Function: Pulling out and indexing the pyramids by 180 degrees adjusts tip-to-tip span from 30 mm (cervical) to 60 mm (lumbar). A single pyramid can also plug directly into the carriage socket for single-point unilateral mobilizations. 60 mm Smooth Thoracic Dome Head: Standard 40 mm bayonet male base. 50 mm Standoff Extension Arm: Bayonet male-to-female extension for overhead arm clearance. Track Webbing & Dual-Point Door Anchoring: Top Door Hook: 1.2 mm stainless steel over-door bracket (45 mm door rebate throat clearance) with webbing slot and 0.5 mm internal relief for protective padding. Bottom Door Anchor: Soft, high-density anchor puck / door jam cylinder (encapsulated in reinforced webbing) that sits behind the closed door leaf to protect floors and thresholds completely. Tensioning: Integration and BOM specification of 50 mm seatbelt-grade polyester webbing, industrial cam buckle tensioner, and strap management keeper loop. CMF & Aesthetic Direction: Design Language: Minimalist, ergonomic, and Scandinavian-inspired wellness aesthetic (matte finishes, rounded tactile surfaces, soft transitional radii, flush pinch-paddles). Must look like an intentional home wellness device rather than an industrial power tool. Production Colors: Base carriage in Matte Anthracite / Slate Grey; touchpoints (pinch paddles) in Subtle Contrast Accent (Muted Terracotta or Warm Stone); attachment heads in Charcoal with high-friction textured tips. Deliverables: Native parametric CAD assembly (SolidWorks or Fusion 360 preferred) + clean neutral .STEP master assembly. Individual production-ready .STEP and .STL / .3MF files for all SLS PA12 printed parts (toleranced with ~0.35 mm running clearances). 2D flat-pattern .DXF file with bend callouts for the 1.2 mm sheet-metal door hook. Bill of Materials (BOM) specifying off-the-shelf COTS springs, fasteners, webbing, and tensioning hardware. Milestone Structure: Milestone 1: 3D cross-section and kinematics of the internal carriage, transverse rocker, spring pockets, and brake shoe. Milestone 2: Modular attachment heads (Dual adapter, indexed eccentric pyramids, 60 mm dome, and standoff arm). Milestone 3: Full assembly integration (Track webbing, top hook DXF, soft bottom anchor puck, hardware BOM, and DFM review). We welcome engineering and industrial design input: the winning engineer is expected to actively identify kinematic blind spots (e.g., anti-cocking brake geometry, snap-detent wear on PA12) and suggest surface-refinement details like flush parting lines and ergonomic contouring to elevate both mechanical reliability and aesthetic execution.