This is a parametric organizer tray where the width, length, and height of an item along with the number of rows and columns holding the items can be specified. Each tray (two are depicted in the photos) can be stacked upon each other. This all started with a similar project of mine to hold cubed cocktail ice apart in a freezer but can be used for whatever items you may choose like playing cards, paper napkins, 35mm slides, etc. 

This stackable model DOES REQUIRE SUPPORTS (Normal-auto, does not remove small overhangs, top z-distance of 0.3) but on my X1C the outside supports easily pop off and the center supports should need a little twist (e.g. razor blade point) to pop them out. If you don't need to stack your prints you will not need to enable supports.