Lens Cap & DIY Filter Cap for GoPro HERO 3 Waterproof Case

this started when i found a piece of leftover polarizing foil at home. to be able to use it for my gopro hero 3 camera, i designed a lens cap with a hole.

with the resulting »DIY filter cap«, you can use any piece of transparent material as a filter. just cut the transparent foil to an approximate dimension and use the DIY filter cap to affix it in front of the lens on the waterproof case.

i made two versions of it, one for very thin films, and a second one for thicker foils (approx. 0