There is a 3d printed case from PLA that I designed in Fusion 360. It uses metal threaded inserts to fix the cover and rubber half-spheres as feet.
The microcontroller inside emulated standard HID to act as a keyboard. Therefore no software or drivers are necessary on the PC side.
The coolest part was making the lettering. I printed letters as valleys. Covered the top with dish soap. Let it dry and applied silicone adhesive. This is the kind that is usually find inside electronics. I smeared it with a finger while wearing gloves. And when silicone has cured it was removed.
What microcontroller are you using?