Oh, I see what you are saying. It would make sense that they are using a similar method. I'm thinking this would be a good application for a Piezo sensor as a alternative to completing a circuit.

I am currently designing a IDEX. I have learned that the Craftbot can align the nozzles by using a round hole on the build plate and I'm assuming stall detection to find the center of each nozzle by bumping it into the hole. I know stall detection is not as accurate as an endstop switch so I have designed them into my x-axis but this would be a cool feature to implement. Does anyone have an idea how Craftbot can make this work? I have not been able to find what stepper drivers they are using on the Craftbot.