I designed this light diffuser and wall mounts for my P10 RGB LED matrix panel but it's parametric and can be modified to fit pretty much any sized panel. Printed in white PLA the diffuser does a fantastic job: It makes the panel easier to read and prevents it from burning your retinas up close (hehe). It also makes the panel more aesthetically pleasing all around.

See it in action: https://gfycat.com/newflickeringcleanerwrasse

Here too: https://gfycat.com/marriedindeliblegrizzlybear

This thing comes with STLs for a 320x160mm RGB LED display along with parts that allow you to mount it to the wall using bog standard household screws (or hooks). The diffuser is meant to be printed in two 160mm parts (each covering one half of the panel). The wall mounts were configured so the panel will sit off the wall about 20mm (to fit any electronics/cabling that might be behind it) but that's parametric too: Just open up the .scad and pick whatever size(s) you want.