With a scrap piece of 9mm MDF, today I carved a filter holder for my trusty time lapse GoPro Hero2 camera. This way I can use a circular polariser filter from my normal camera on the GoPro.
It’s just push fit over the GoPro lens and the filter push fits into the holder. I might do it again in a slightly softer material to make the push fit easier and more secure.
Video result (over done to demonstrate)