Why would you ever want to do that? Polaroid 100/200/etc. cameras for the Fuji packfilm can be had for $5 and are easily converted to pinhole. I've done it once or twice, and the film is better and more readily available than Instax. If you must, gut one of those packfilm cameras and tear off the back for your Instax processing. The rollers will work better than anything you could cobble together from the hardware store.
Originally Posted by philpem