I needed some microscope slide trays for my students, so I made these. The large trays hold 20 slides, while the small one holds 5. They work surprisingly well. Also, they print very easily at 0.2 mm layer height & 15% infill, no supports. One of the large trays has numbered slots; however, I didn't need this so I didn't test print that one. The large ones use about 60 grams of filament depending on your print settings.