Silicone Knuckle-Crack Fidget Prototype

The concept is already sketched and hand-mocked: a palm-hugging silicone shell with shallow finger ridges that compresses through two stages—first a gentle preload, then a deeper “crack” that mimics knuckle popping. What I need now is a production-ready design that preserves that comfortable in-palm feel while reliably producing the audible snap and repeatable tactile release that make the toy addictive.

Scope of work
• Translate the rough geometry into full 3D CAD (SolidWorks, Fusion 360 or comparable) with accurate wall thickness, venting and gate positions suited for liquid-silicone molding.
• Engineer the two-stage dome so that Stage 1 offers smooth resistance and Stage 2 emits a crisp, repeatable crack; material durometer, internal voids and membrane thickness all need tuning.
• Validate the acoustic profile in simulation or bench testing—I want the sound of cracking to be unmistakable without amplifying unwanted squeaks.
• Provide a DFM package: mold split lines, draft angles, and a suggested tool steel and surface finish that balance part release with durability.
• Ship one functional prototype (own shop, service bureau or RTV mold acceptable) for real-world squeeze testing.

Acceptance criteria
1. Fits comfortably in an average adult palm without hard pressure points.
2. Produces a clear “crack” ≥ 60 dB at 10 cm distance in a quiet room.
3. Maintains at least 5,000 squeeze cycles with no audible degradation or tearing.

I will supply existing sketches, rough dimensions and notes on shore hardness ranges already explored. The project wraps when the CAD, DFM files and a working prototype prove the comfort-focused ergonomic shape, the tactile feedback I’m chasing, and—above all—the signature cracking sound.