Doing this project and using this cartridge can be a little detail oriented. It requires more attention to detail than the 120 cartridges.

Printing up the parts

Download the 3D files here and print each of the files using supports and 3 top and bottom layers for light tightness. You can also send the an STL file with all the pieces to any print service (try Craftcloud3d for a pretty good quote in your area), or you can order them from PCBWAY which quotes around $38US for this project.

Preparing the parts

Insert the drive gear in the upper left of the cartridge. It'll install with a gentle snap. Mount the thumb gear in the two holes to the right of the drive gear with a small screw or pin (an old Polaroid hinge works) and be sure it turns the drive gear easily.

File the ridges and uneven surfaces (from the supports) off the roller ends and sand the right roller with 100 grit sandpaper to give it some friction so the film won't slide over it, instead causing the roller to roll while the film is being advanced. Snap the left roller into place. It's a tight fit so do this with care to avoid breaking anything. Clearances are small since alignment of the film over the film mask is critical. Insert the top end of the right roller into the pressure plate, then insert the shaft of the small 13 tooth gear through the hole of the pressure plate counter box into the roller end. You may want to verify that the shaft will insert snugly before installing it, but be careful not to break the shaft. If you filed down the shaft too much so it slips in easily, use some glue to secure the shaft inside the roller. Center the gear inside the gear counter box.

Mount the exposure indicator gear above the counter gear with a pin or screw, being sure it engages OK and doesn't jump gears or bind. If it is not aligned correctly, raise/lower the gear by rounding out the shaft holes in the pressure plate, then melt in place. Test the counter gear by rolling the right roller and seeing whether it engages freely, but doesn't jump off the counter gear.

Remove the original back door by removing the hinge (you may have to remove the plastic pieces at both ends of the hinge) and install the new door. It may be tricky to align the hinge while inserting it. It would be best to insert the hinge pin into the 3D printed door before installing it, to ensure the print left enough room for the hinge. Close the door while pressing on the release latch and be sure the latch engages securely. If the latch doesn't seem to return freely, file a bit off of the bottom and tip of the latch hooks on the back. Be careful as the hooks are somewhat fragile. You can either cut/glue a red filter over the film counter hole, or you can place a piece of black tape over it to prevent light leaks through the exposure counter hole.

Line the top edge of the film compartment with 2mm black craft foam to prevent light leaks from the top of the door. Alternatively, you can glue a piece of craft foam onto the outside of the cartridge, butting it up to the top of the film bay while it's installed in the camera.

Using the 35mm film holder

An empty 35mm canister is used to takeup the film instead of rewinding it back into the original cartridge. The alleviates the need for a rewind knob.

To make most use of the film, tape around 5 cm (2 inches) of leader to the film spool that will be loaded with new film. Then, tape the new film end from the bulk loader to the leader with one piece of masking tape on one side only, not folded over the edge. This is so it will release and untape so the end of the roll can be rolled into the take up cartridge. Load it with the bulk loader with 26 turns, which will give you 12 exposures. Alternately, you can just use a new roll of film and cut off the swooped part of the leader.
Tape 20 cm (8 inches) of leader to the take up spool and tape this to the loaded film end using 2 pieces of transparent tape, one on each side, not folding it over, keeping the sprocket holes open. You'll waste 2 frames if you don't use the leader. Lay the film out across the cartridge emulsion side down
Align the exposure counter gear so the O is at the top (or slightly to the right) by moving the right roller.
Insert the pressure plate into the cartridge, making sure the film is between the outside ends of the rollers.
Install the drive spool onto the top end of the take-up cassette and flip the cassette over onto the pressure plate, tipping the top onto the drive gear while inserting the drive tab into the drive gear. Move the wind knob until it's aligned with the tab. Be sure the cassette is seating securely in the indent in the pressure plate. If it doesn't seat correctly, you may need to file the top of the drive spool.
Flip the full film cassette into the right indent of the pressure plate being sure the film is seated between the roller ends.
Place the covers on each end and make sure they are flush with the top of the cartridge.
Turn the cartridge over and verify that the film is seated and centered under the film mask. if one side is caught, push gently onto the film/pressure plate to give it room and center the film. Advance the film slightly to be sure it moves freely.
Insert the cartridge into the camera and close the door, making sure the latches are seated correctly.
Wind the film forward until you reach the l mark, then wind the film one more revolution until the l mark appears again. You are ready to shoot.
At the end of the roll, if you bulk loaded the cassette with one piece of masking tape, you'll feel some resistance. Try advancing the film until it breaks free. If it's too difficult, or if you are using commercially loaded film, leave the cartridge inside the camera until you can unload it in a darkroom, otherwise you'll lose your last 2 exposures.

Feel free to contact me with any questions or news about your build!