Remixed the cover for a 4 Inch touchscreen, using the excellent HyperPixel 800x480 capacitive touch screen.
The screen slides under the holding clips snugly, gently bend the part to slot the screen under the second set of holding clips, then attach the Pi.
Text stl file included for the MMU-ness
And yes, it's about 9mm off-centre, but I don't care, spent way too much time on this already!
Supports from the build plate, only underneath the brackets. Used the "support blockers" in PrusaSlicer to inhibit supports around the bevelled edges