UPDATE! I have added GC_e3d_Capture_Side.stl and GC_e3d_Exturder_Side.stl. These mounts can be used on the RB to mount an e3d (single or dual) without the need to modify the aluminum mounting plate. Used with the risers, you have a simple zero z-loss e3d solution. These risers can be used to raise your extruder plate to allow mounting your E3D-v6 hotend without loosing any Z axis. You will need to slightly modify your mounting plate (if you don't use the GC mounts) as shown in the image to allow room for the hot-end heatsink. Credit goes to Tom Carson for the clamp mounts I have included from http://rigidtalk.com/wiki/index.php?title=E3Dv6_Hotend_Mount. I slighly modified the extruder half of the mount to better align the holes for my extruder plate. The original can be still downloaded at the wiki. I use M3 x 35 machine screws for the risers. I purchased them at a local hobby shop.