CTC Replicator Overhead Spool Holder

When mounting spools on the back of the printer I often had trouble with the loop of filament going to the print head getting trapped underneath another loop. Since changing to this design I haven't experienced that problem. For each spool you will need a holder, a mirror image of the holder, two tubes, two spool bushes and two threaded bushes. The spool bushes are intentionally a loose fit on the metal tube, this puts the centre of gravity of the spool below the axis of the tube. The result of this is that when the print head moves away from the holder it raises the c of g of the spool creating tension so that when the head moves back towards the head the slack in the filament is taken up. The spool bush is designed for filament spools with a 58mm diameter hole but I've included the OpenScad file for this part so you can customize it to suit other spool sizes.
When I first posted this design I forgot to mention that I was using filament guide https://www.thingiverse.com/thing:616895