he smt reel is advanced via pulling the tape. The tape is ~0.1mm thick according to vishay so i made the slot where the tape goes trough small. Immediately after the tape is pulled of the top is closed so components cant fly out of the carrier. At the end there is a slot where the components can be picked via the pnp.I have looked at rotary encoders , magnetic encoders ... but they are all to expensive. There is also the button method or IR port method. But I think there are things that can go wrong with that setup.A small and cheap stepper motor + driver (with microstepping) is one of the best solutions I can think of at the moment. I currently do not have smd components with me so I cant test it at the moment.Currently printing and probably modding it.