Super cool X carriage 9004

I reworked my 9003 carriage for the Robo3D R1+ with the E3d Titan Aero hotend/extruder. This has much better fitment, a cable restraint, better airflow from the rear duct and now dual ducts! It's a small cyclone just under that nozzle! Like the 9003, it keeps the mount for DC42's fantastic IR probe, adjustable belt tensioner, and the adjustable Y-min.