nplus is actually not joking; it can be done by slamming it down, (works for beer too, sort of). They make reusable cannisters for loading your own film. It's really cheap in bulk, and you can load shorter or longer rolls. For reuseable you want to open by slamming; a bottle opener will bend it. I also have seen a special tool; sort of like a pincer with a round cutout. But bottle opener works just as well. Do yourself a favor and buy a metal reel and tank for developing. It looks harder to use than the plastic ones, but is actually easier with practice. Remember to switch off the light. ;-)