I made this adapter to spool 35mm onto a 620 format spool for my vintage Kodak Vigilant. This will work for any film camera that requires 620 film: 645, 6x6, 6x7, 6x9, 6x17 etc.

Print 2 of these and spool loose/bulk 35mm film on one, then thread to the other as a take-up spool.

This will produce an image over top of the sprocket holes, basically a panoramic image. Make sure to spool and load the film into the camera under COMPLETE darkness, not even under a safelite [I know this from experience :( ]

This is a reupload of my model on thingiverse: https://www.thingiverse.com/thing:2958619

Check out this model for a corresponding holder for a 35mm canister if you prefer that: https://www.thingiverse.com/thing:3471699