OmniGrip: Universal Flexi Key Turner [FullTurn]

No screws, no adjustments, zero tools: an adaptive multi-material assistive device engineered with an elastomeric matrix of flexible TPU pins that automatically molds around standard house keys, thick vehicle keys, and bulky electronic fobs.   💡 The Story & Engineering Challenge Operating physical keys—starting a car ignition, unlocking a front door, or turning a stiff security deadbolt—demands significant pinch force, fine finger dexterity, and wrist torque. For individuals living with arthritis, reduced hand strength, tremors, stroke recovery, or upper-limb differences, this routine task can become a painful barrier to independence. Most commercial or 3D-printed key turners on the market share critical flaws: Frictionless or Fixed Slots: They rely on narrow, rigid slots that only accept standard thin keys and fail completely with modern car fobs or thick plastic-headed keys. Complex Hardware: They use small screws, bolts, or clamps that require the very finger dexterity the user lacks just to install or swap a key. Single-Key Lock-In: They lock the user into carrying a single dedicated key holder.   OmniGrip solves this with inspiration from universal flexible-bristle mechanisms: a densely packed matrix of resilient TPU 95A pins that flex laterally when pressed against a key, forming a custom, high-friction mechanical lock around any irregular profile, while an anatomical rigid shell multiplies torque for effortless turning.   ✨ Key Features Universal Auto-Adaptive Grip: Instantly conforms to residential flat keys, double-sided automotive keys, security deadbolts, and thick remotes without swapping inserts or adjusting hardware. Zero-Tool, One-Handed Operation: Push the key into the flexible pin core with a simple downward press; pull it straight out when finished. Completely operable with a single hand. High-Torque 5-Lobe Anatomical Handle: Converts difficult pinch-grip force into a comfortable whole-palm or fist rotation, drastically lowering the physical torque needed to turn stubborn cylinders. Dual Manufacturing Options:Two-Part Modular Hybrid (Recommended): Rigid outer shell (PLA/PETG) for structural stiffness + flexible core (TPU 95A) for grip. All-in-One Monolithic Print (100% TPU): A completely unified single-piece print with a solid, closed bottom for users who prefer full elastomeric handling. 10-Tooth Anti-Rotation Spline: The modular version features a calibrated internal 10-tooth star engagement that locks the insert mechanically to the outer shell, eliminating rotational slippage under heavy loads. Modular & Sustainable (Quick-Release Ejection Port): The 12 mm opening on the bottom allows instant, tool-free maintenance. Simply push a standard pencil or pen through the bottom hole to pop out the TPU insert. If the pins ever wear down or you need a different profile, reprint only the 15 g flexible core without discarding the rigid outer shell. Streamlined Parametric Customizer (5 Core Controls): Designed in OpenSCAD with zero clutter. Users and occupational therapists can customize only the 5 essential variables via the MakerWorld Customizer without risking broken geometry:Outer Handle Diameter Cavity / Pin Bed Diameter Pin Thickness Pin Height (Insertion Depth) Pin Center-to-Center Spacing   🖊️ Dual-Use Accessibility Bonus: "Grab & Go" Vertical Desktop Stand When not opening doors or starting the car, OmniGrip doubles as an assistive desktop stand! Picking up thin pens, pencils, stylus tools, or eating utensils lying flat on a desk demands fine fingernail coordination and pinch strength that can be painful for individuals with arthritis or motor limitations. Dropping pens or tools into the flexible TPU pin matrix keeps them resting upright at a natural angle. Users can grab them effortlessly using a relaxed, full-hand palm grasp directly from the table. One print, multiple daily independence wins.   🛠️ Print Profiles & Slicing Recommendations Pre-configured 3MF plates are available for direct printing. To print from individual STLs: 1. Rigid Shell (PLA or PETG) Layer Height: 0.20 mm Walls / Perimeters: 4 (ensures maximum strength across the drive lobes) Infill: 25% – 30% (Gyroid) Supports: None (prints completely flat on build plate) 2. Flexi-Pin Insert (TPU 95A) Layer Height: 0.20 mm (essential for layer bonding under bending loads) Walls / Perimeters: 4 walls (this prints the pins as 100% solid concentric rings, providing maximum torsional resilience) Infill: 100% on the base plate Outer Wall Speed: 25–35 mm/s (for crisp pin tip definition and minimal stringing) Cooling Fan: 100% 3. Monolithic Version (100% TPU 95A) Use the all_in_one_tpu mode in the OpenSCAD file: generates the full lobed body with an integrated pin bed and a smooth, solid closed base.   🔧 Assembly & Tool-Free Replacement Assembly: Align the 10-tooth spline on the TPU insert with the internal splines of the rigid shell and press firmly into place until it seats flush. The calibrated 0.05 mm tolerance provides a firm interference fit that stays secure upside down. Disassembly: Insert the blunt end of a pencil or pen through the bottom 12 mm port and push gently to release the core.   ♿ Design Contest Compliance (FullTurn Brief) Engineered directly to satisfy the evaluation criteria for the FullTurn Challenge co-hosted by Makers Making Change and MakerWorld: Leverage Amplification: The 5-lobe contour eliminates tight pinch grip, allowing full palm or knuckle actuation. Universal Geometry: Accommodates asymmetric, standard, and thick electronic key heads with zero adjustment. Non-Destructive: Requires zero adhesives, alterations, or permanent attachments to original keys. Accessible & Open: Fully customizable via OpenSCAD and printable on standard desktop FDM printers without complex multi-material feeding systems.