Spool Holder for Prusa i3 / MK2 - Fast spool replacement - Back position

There was a problem with the original Mark 2 design with tall pieces if you have the cables in a chain, it would touch the supports and limit the movement of the chain.

Only changed the arms to a backward position, with the arms enlarged by 15 mm. A possible improvement would be to lower the position of the spool.

I recommend to print with 50% fill, scaling up the nut by 1% in Cura and to lubricate the screw with some oil before attempting to join them (not too much flow is important; 103%