Dactyl-ManuForm
Parameterized, split-hand, concave, columnar, ergonomic keyboard
...The walls were changed to just drop to the floor. The 3D printed part is the main keyboard. You can attach a bottom plate with screws. The case has holes for heat-set inserts designed to hold 3- to 6-mm long M3 screws. Then, I used wafer-head screws to connect a bottom plate. If wires aren't dangling, a bottom plate may not be needed. You need something on the bottom to keep the keyboard from sliding around. Without a plate, you could use a rubber pad, or you could dip the bottom of the keyboard in PlastiDip.