Snap-Fit Cap Refinement Prototype

I have a working 3D-printed prototype of a small handheld skin-care device. The removable cap currently relies on loose friction; I need it converted to a positive locking press-fit or snap-fit that feels purposeful and stays put when the unit is placed in the freezer, yet can still be removed comfortably by hand.

Here is what I’m after:

• Re-engineer the locking mechanism (snap-fit or press-fit) so the cap audibly or tactilely “clicks” into place without an O-ring, allowing for a slight internal air gap to absorb thermal expansion.
• Tidy up the surrounding geometry so the surfaces are smooth enough for direct silicone mold casting—no sharp artifacts from the original print.
• Supply a clean, production-ready CAD file native to Fusion 360 or SolidWorks, along with exported STL.

My workflow is simple. I’ll share reference photos first so you can outline your approach. Once we agree, I’ll forward the full CAD/STL files for you to revise, then test-print your updated design here and give feedback for one round of tweaks before final sign-off.

If you’ve solved similar enclosure or consumer-product fits before, especially where cold-cycle reliability matters, show me a quick example and walk me through how you’d tackle this mechanism. That experience will be the main deciding factor.