Every day I do a little more. Today I finished machined the toothed idlers, by boring the 5mm stock I.D. out to 11mm and then turning the nose off on a lathe to make perfect idlers from these that I got from eBay: http://www.ebay.com/itm/231825108382 and http://www.ebay.com/itm/291694937751
Only the motor mounts and drive pulley brackets left to design. Will be bolting it all together soon so I can start on the wiring. The software will be RepRap/Repetier with modifications to support the dual CoreXY drive.