Update 24/05/19: Forget about my design, I would encourage people to have a look at the design linked below instead, looks much better than what I have attempted here.
This is an untested design, do NOT expect this to work yet, just sharing to see if ppl comment and provide valuable feedback.
This Is my 1st attempt designing a Hotend Mount for the Titan Aero on the Rat Rig V-Core. I have taken the original Fusion 360 design and maintained the belt tensioner as base plate and added the Hotend Mount as individual part to be able to easy swap it if needed. The PTFE Tube holder is made for the Threaded Bowden Coupling with 1/4" thread, its intended to hold the PTFE tube on the Rat Rig frame and have tubing between the hotend and where I have the filament spool beside the printer. The idler lever on the hotend will take the other end of the tubing, its designed for that. The small cable mount plate is intended to hold the original E3D connectors for the termistor and the fan in place and the heater wires and provide strain relive. It will fit my stepper motor with a cable tie, I am not sure if it will work with the original flat-pack E3D stepper.
Its printed quick and dirty in PLA with 15% triangular infill just as a test fit, the final print would be ABS or PC with more infill.
I will have to add some keying to the flat back, the bolts alone wont keep it at a precise position once unscrewed and reattached. I am also thinking of having belt tensioner entirely separate on one side of the cart and have some form of metal cones or maybe even Delta type magnetic balls on the other side to have a reproducible precise fit and also be closer to the center of the gantry with the nozzle and weight. Maybe a spring pulling it in place instead of fixed bolts as long as I have a shape for precise positioning.
I have now mounted my prototype design to the actual Ratrig V-Core. I looks as if I have to design it to bring the nozzle a little bit down. The bed can not raise high enough for this because it was originally designed to have a E3D V6 hotend which has the nozzle a bit lower (closed to the bed). Also in the mount base I have forgotten to leave room for the heads of the bolts and the PTFE tube mount is to flimsy. I will update the files as soon as I have a working design.