Yet another filament spool

I had some big (3kg each) spools of Herz PLA filament. Those need large and strong external holders. There were no way to put one on my simple (and weak) CTC printer.
I had some PVC tubes nearby as well. With OpenSCAD it needed few minutes to design a joint and a plug to complete this simple filament spool holder.

The design could be easily modified for different tube inner and outer diameters in OpenSCAD. The lengths of the tubes depend on the spool diameter and depth. Since PVC tubes are n