So after seeing the XChange I had the idea of maybe using PCB boards to implement an automatic tool changer. PCBs can be thick, are precise and cheap and easy to order. 3.2 mm circuit board would be plenty strong and stiff. Maybe you could insert and SMD solder the registration points for precise positioning. Like a ball and those bars on the E3D toochanging plates. You'd put both "halves" into the reflow oven to assure precise registration You could have a functional PCB where you just need to solder the mechanical registration points and the electric connector. In the simplest case that would just be pins sliding into some sort of socket (something like mill-max sockets). For the tools you could also save on wires to accommodate LEDs or temperature sensors or filament sensor. Maybe?