Filament Holder for Printer Enclosure with 30 mm Aluminium Tube

This is my filament holder, screwed to the top of the enclosure of my Prusa-style printer. I got the aluminum tube from a local DIY market (Bauhaus in Germany). The tube has a diameter of 30 mm and snaps into the printed holder. Of course you need two of the printed holders. ;)

I added a bit grease to the tube to reduce the fraction of the spools. Works fine for me.

123D Design file is added.