Wearable Skin Tension Device CAD Design

Hi! Here's a quick overview of the product so you can quote it: WHAT IT IS A small, wearable device that gently stretches skin over time. HOW IT WORKS - Two adhesive pads stick to the skin a short distance apart - The pads are connected by a rail - The user slides the pads apart to add tension - A pawl (ratchet) locks the distance so the tension holds - A simple release lets the user back it off or remove it DESIGN GOALS - Low profile and lightweight, so it can be worn under clothing - Easy to adjust with one hand, in small, clicky increments - Pads can follow the curve of the body - No sharp edges against the skin - Simple enough to 3D print for prototypes, and later to injection mould WHAT I NEED FROM YOU - A full 3D model in Fusion 360 - Native .f3d files plus STEP files - Print-ready files for a first prototype - A couple of clean renders I'll send hand sketches once we've agreed on terms. I'd also ask you to sign a simple NDA and confirm that I own the design files. What would you charge for this, and how soon could you start?