I've been goofing around with my old 70's childhood camera. It's a square format that take 126 film cartridges that they don't make anymore so it's been sitting on the shelf.
I found mention of running regular 35mm cannister film through it so I tried it. After notching the top with a blade, you tape the end of the film to something cylindrical (I used a marker cap) and then in the complete dark, pull the film out of the can until it stops at its end and wind the film around the marker cap, then jam both back into the camera. You're going to get light leaks so you may need to use electrical tape if you want. Besides the window and one side, I left the gaps alone so I could get some leaks through. The results could be all over the place. Especially if you use expired film. I'll add some of my results here.
Expired Agfa 400
35 in 126 by
No Stone Unturned Photography, on Flickr
Expired Agfa 400
35 in 126 by
No Stone Unturned Photography, on Flickr
Very expired 100 slide film
35 in 126 by
No Stone Unturned Photography, on Flickr