A 7.5cm threaded shaft carries two nuts on opposite-thread grooves that move against each other the moment you turn it. One nut climbs right while the other slides left, and the whole thing fits palm-sized in your hand. Every unit comes in its own random colour mix, so no two look alike.
Sit it between your fingers and twist the shaft one way, then the other. The nuts race apart and rush back together in a smooth, unbroken loop that is almost impossible to stop once you start. The dual-thread grooves engage in a smooth motion that rewards slow, deliberate motion.
Visitors lean in when they see the nuts moving in opposite directions, and the first question is always how it works.









