I bought a shadowbox from Hobby Lobby to put my Gameboy Color consoles in, but I found that sandwiching the consoles between the felt board and glass didn't work well. The buttons were pushed in permanently which I worried could damage them, and they tended to slip around. I want to preserve these Gameboys (not destroy them), as I want them to be playable in the future.
I searched for a satisfactory way to mount them, and ultimately had the idea of mounting them from the cartridge slot. The result is a printable cartridge that has holes for screws. These shouldn't damage the Gameboys, because they're the exact same dimensions as a cartridge.
Be sure to read the post-printing instructions before trying to install these.
I'm also including little tabs for the back of the shadowbox that allow for a bit more depth, and hold the back on securely. Flip the included tabs on the shadowbox outward to hold it further back, and then install the printed tabs on the back to hold the felt board in place.
Ensure that these prints are accurate with no rough layers, and be sure there is no over-extrusion. I printed these at 0.15mm layer height at 97 percent flow (my Prusa MK2S tends to overextrude a bit) to ensure that they would be dimensionally accurate.
I recommend wet sanding the cartridge-end with some 320-grit or similar sandpaper.The idea is just to knock down any rough parts. They should be dimensionally accurate, you just don't want anything rough scraping the cartridge slot or connectors on your consoles. Use extreme care the first time you install them. Every printer is different so while I believe these models to be accurate, your results may vary.