Some days ago I had an idea. Using electromagnets instead of servos or motors.

As I only have 3 electromagnets at the moment the first test is pretty simple. But it works!

Using an Arduino Uno and 6 relays the polarity of each magnet changes from negative to positive or vice versa. One magnet pulls and the other two are pushing.

Hope to get some more magnets soon (and stronger ones) to do more testing.