Filament spool holder for Prusa i3 Hephestos

Original construction is too stupid (too complicated to switch filament), so I designed an holder which I don't have to remove to switch the spool. And, yes, the original middle tube is just to small for some 3rd-party spools, so I also increased the size of that.

Unfortunately, no images yet as I couldn't make it yet (had some issues with my printer), but this is my next thing to do :) After that, I might do some slightly changes to parameters, but for now I tried to include some tolerance.