I loaded up my Holga 120S using 35mm film. It's a pretty easy process. I used foam to keep the 35mm cartridge steady on the left side and taped the leading strip to the take-up spool on the right. Because I left in the 6 x 4.5cm piece in the Holga, I advanced each frame at least 1.5 rotations each time. If you take it out (for 6 x 6 format) wind at least 2 rotations. Using the 6 x 6 format gives the most dramatic "wide" results. When the roll is exposed, manually rewind the film into the 35mm cartridge in complete darkness.

At the lab, I had them make me a contact sheet. It came out terribly, even for a Holga experiment. Red monopolizes all the prints. I suspect I poorly covered up the red plastic screen in the back. Winding was a disaster.

Dave Pierson did the same experiment (technical details), but he scanned his negatives with a negative scanner with good results (gallery). Kim Taylor (web site) worked some magic with 35mm film in her Lubitel. She printed the negatives the old fashioned way.