This is a two part project to make a 4x5 dark slide. The handle must printed vertically so that the slot for the  slide stays open during printing. There are four raised nubs on one side to indicate whether the film on  that side of the holder has been exposed, as many older holders have: easy to manage in the dark. Multi-color printing won't work in that orientation so I went with that approach. 

A friction fit is pretty snug but a dab of cyanoacrylate will make it permanent. A smarter designer would have photographed both parts before assembly but all you get is me, I'm afraid. I have tested for fitment in the varying vintage holders I have it and it works. 

NB: the slide was printed at a .07mm layer height with a final thickness/height of .7mm, equivalent to a commercial dark slide. I used PLA for stiffness. You could perhaps get away with .1mm; 7 layers should still be opaque at 100% infill. 6 hours is a long print time if you are still using a MK3. I used PETG for the handle but that makes no difference.