Here's a small shelf I made to hold a Raspberry PI under my desk. It probably could be used to hold other things fitting the volume.

I churched it up a bit with some "Voronoi" patterns on the sides. I did this to allow the air flow from the cooling fan to be able to exit easier. They also help a bit on filament consumption, but some of the larger holes can get a little messy. Most of that could probably be resolved by someone with even a modicum printing experience.

The OBJ file included is a plain version of the shelf before I had at it with all the fillets, rounds, and holes.