Simple slide holder w/ an m4 screw you can use to adjust the height. I used it to photograph a bunch of 35mm and 126 slides with a macro lens.

It's mean to be attached to a mounting plate with a camera at one end and a 4.2mm ish slot for the holder to mount to on the other. The distance you need being dependent on your cameras sensor size, your lens working distance, and the size of your slides. I don't have files for the plate because it was substantially longer than I could print (I used a 100mm macro lens), so you're on your own for that part.

Though the whole process was a pain, I got my slide converted and the holder worked fine. If I had it to do again I'd try making a form fitting camera mount for the other end to keep it from being able to rotate on the tripod screw.

I printed it without supports and used force to get the nut all the way in (I recommend using a soldering iron but I was lazy), getting it out again will require violence.