Anti oozing Dual Hotends for Rebel II 3D printer

This extruder is based on one guy design from Rebel II forum. Original design used direct driven extrusion, but I did not like it, because I would need to rebuild half of printer so I have chosen to use bowdens and put extruders on construction. You can use as extruder any bowden extruder you like. These dual hot ends are basically designed for my Rebel II printer www.rebelove.org, and normal 3Draty hotends www.3draty.cz, but design can be easily altered for using other printers (for example Pru