Filament Guide for Mendel90 - fits on a 3mm sheet

My filament liked to collide and get caught by the upper right Z axis, so I did an OpenSCAD thing which fits at the top of my Mendel90 and keeps the filament in place. It will probably fit on any 3mm plate. If you need another size, maybe for a 5mm acrylic sheet, it will be easy to adjust. The thing is done "Quich and Dirty": no optimization, no rounded corners or similar.
Simple cubes & cylinders. 2 plates at the sides, one ring to guide the filament, and a cross in the middle to stabilize. 4