PLA Prototype to Manufacture-Ready Rigid Shell + Silicone Overmold

Mechanical/Product Design Engineer — PLA Prototype to Manufacture-Ready Rigid Shell + Silicone Overmold

Overview

We have a working 3D-printed (PLA) prototype of a small electronics case with an internal sliding compartment, custom PCB, embedded magnet, and Hall-effect sensor. We need a mechanical/product design engineer to redesign it into a manufacture-ready rigid shell with a silicone overmold, and deliver a finished, consumer-presentable prototype for user testing.

What we need done

Redesign for manufacturing (DFM): Convert the existing case into mold-ready CAD — a rigid inner shell housing the PCB, battery, magnet, and sensor, and forming the sliding compartment mechanism, plus a silicone overmold over the exterior for grip, shock absorption, and water resistance (leaving the moving compartment free of overmold). Include proper wall thickness, draft angles, mounting bosses, and undercuts for a secure silicone bond.
Material and process spec: Document the recommended rigid substrate material, silicone/LSR grade and hardness (Shore A), and bonding method — clear enough to hand directly to a manufacturer for quoting.
Manufacture-ready files: Final CAD in native and neutral formats (e.g., STEP), with separate parts for the rigid shell and overmold, ready to submit to an injection molder (e.g., Protolabs, Xometry, Fictiv, or an overseas manufacturer).
Finished prototype: A working unit (or small batch, ideally 3–5) with the rigid-shell-and-overmold construction and our existing electronics integrated. The final product must be genuinely consumer-ready in look and feel for hands-on user testing. For this project—a phone case—it is critical that the delivered product is finalized as "one-and-done," requiring no further iterations or adjustments after delivery.

What we're looking for

Proven experience designing plastic/rubber parts for injection molding and overmolding specifically (not just general CAD work) — please share examples of past projects where you took a design through this exact rigid-plus-silicone-overmold process.
Comfort working with small mechanical assemblies (sliding/drawer mechanisms, embedded magnets, PCB mounting) inside a consumer electronics enclosure.
Ability to either produce the physical prototype yourself or manage sourcing it through a rapid-prototyping manufacturer (Protolabs/Xometry/Fictiv or similar) on our behalf.
Clear, organized documentation habits — we need the process spec to be something we can hand to a factory later without you in the room.