A 49mm lens cap that I made. Works great with my Sony lenses. Be careful to use this lenscap with too rounded lenses as the backside of this lens cap is flat for easier printing.

I made a lite version, see "49mm_lenscap_V3_lite.stl" which requires less force to remove and put on, it will however fall off easier.

I did some quick simulations, more for fun than to check the model:

Total displacement

Stress von mises

No

No