This is a basic spool for 120 film. This should be fully usable, and you should be able to use it to wind film onto. Measurements were taken from an existing 120 film roller, so I believe everything should be within specification.

The model was created in Blender. I had some difficulty with the Boolean operations. Some operations left the mesh in state unable to perform subsequent operations on without modification. Please let me know if the resulting mesh has issues. I'll test it out when I have access to a printer.