I found this modified Holga 120N at a thrift store. I was suprised to see an extra knob on the bottom of the camera when I picked it up. It is a rewind knob from another Holga that has been mounted to the bottom of the camera to rewind the 35mm film without having to go into a darkroom, or put the camera in a film changing bag. The blue tape was on the camera when I found it. The counter window has been blocked out and the winder knob has some markings to help the shooter figure out how far to wind. A bit of sponge in the film compartment keeps the 35mm cassette in position.
I don't know who did the original mod, but it is cleanly and elegantly done. I may have to try doing this mod myself.