Hello, first of all very nice design.
I have a little issue here, I tried with openSCAD to modify the ScreenHolder_v5 file like you explained in order to use it with A4 paper.
But after I changed the commented paper type and regenarate the scad file the left part is floating in the air.
I'm quite new here and don't really know how to lower it.
Thanks in advance for your help and sorry if I made mistakes, it's not my mother tongue :)