Printed from PLA (a mistake, use PETG or ASA because mini pc is becoming quite hot), 0.55mm layer, 0.8mm nozzle, 15% infill but any other settings will also work fine.

Device (even without mount) takes more than 1U unfortunately.

Original bottom screw replaced with M3x10mm one (optional but holds device in place).

Design source files attached (fusion 360 and step).

Edit: tighter model added. Stop print at 10% and see if it fits well for your device. Then print it fully.