Drew up and printed some covers for Digitone/Digitakt with a channel for a strap. The size requires a print bed with dimensions approx 220mm x 220mm. A Prusa i3 type printer should be able to handle it. You could even send the file to an on-demand print service.
I used PETG for the print. Other filaments should work, but I recommend against PLA since it could potentially warp if exposed to direct sunlight.