At first, I designed this to create a dry shooting range at home to practice for USPSA competitions. I couldn't find anything similar, so I quickly put one together using Tinkercad.

This applies to most single-layer corrugated cardboard. I believe it also applies to various other related projects.

I suggest printing with a layer height of 0.3mm and a wall thickness of 3 layers. The infill rate doesn't matter much, because it will print as a solid at these settings. If it doesn't, please select 100% infill.