I got tired of paying $15-25 every time I had water get into my taillights for new gaskets, so I modeled this using my OEM one, and spent near that in prototype prints.

Print in TPU, use the minimum wall count you can get away with and low infill, keep top and bottom layers reasonably thick so it stays waterproof.

I will be using clear silicone to further seal them once installed on the car.