Modelled in tinkercad
Printed on an UP300 (white) and UP mini2 ES (black), no raft, no supports.
The black lifted in one corner, thus the curve.

Requires 4 x ~2mm self tapping screws about 12-13mm long.

You may have to clean out the holes a bit with a drill or risk cracking the print.

Don't overtighten it.

I tried to reinforce the screw hole things to prevent them ripping off... seems to have worked?

I downloaded the official PCB model and basically made it bigger, cut a pcb shaped hole in a box, made that tall, and then used that large hole to cut another square into a pcb shaped housing.

Then i hollowed it out, added holes for buttons, the LCD and the ports, and speaker.

I then modelled the buttons, added the screw holes/standoffs, and printed.

It didnt fit. It was too tight and the screw holes snapped off.

I made the hole for the PCB bigger, by using the pcb model as a hole.
I then reinforced the screw leg things and voila!