This a tray for 30x2mm discs. I use this for storing and displaying filament sample chips. There's a hanger hole and the slots are at 45 degrees so it can lay flat on surface or be hung up and the chips won't fall out.
After receiving a new filament, the first thing I do is print a "test chip". It's a quick, ~10 minute print useful for getting a sense of how it prints and how it looks after printing yielding a nice little sample for reference. Of course, I needed a place to store the samples.
Along with the tray model is the chip that fits it.
Slicing Recommendation Sliced as-is, this is a long print because of all the little slots (20+hrs). However, it's been designed to be "all walls". So you should be able to print face (i.e. slot openings) down with 0 top layers and 0% infill to shave off a few hours. I've found it's plenty rigid for the purpose it serves printed that way.