This got me thinking.

This got me thinking. Rather than having a single or dual head what if we borrowed an idea from old multi-colour xy plotters? They’d draw in one colour then motor to a side to drop one pen off and pick up another. If heads could be made interchangeable via a simple but precise mating mount you could switch from one colour or material to another for printing, change to a component picker, milling head, etc.

This has been done. Heck, someone just did it this week - scroll down the community page, there’s a post that uses electromagnets to park heads.

Aka tool changers - they are an incredibly common concept in CNC applications.

The "simple but precise part is hard, although big magnets can help.

Hmm, I wonder it this will bring back the Morse Taper or something like it. Only problem will be unsticking.

Missed that @ThantiK ​, will have a hunt, thanks.

3D-Proto’s Dual Parking Extruder? Similar, but I’m thinking more than 2. And done in such a way that you don’t have to worry about the offset of having one to the left or right like his.

What you need for N is some kind of reliable transfer and docking mechanism, and I can’t believe that’s going to come easy or cheap. Although the fact that your head already moves in 3D helps a lot. It would be really cool if you didn’t need a separate stepper for each head, but I’d hate to be in charge of that project without a really good machinist.

I wouldn’t say this is the same as the 2 electromagnet parking heads.
The closed loop is really the best way of controlling a bot its just the price was always the problem.