A slender shaft features two threads with two rings riding on it. The round flat end marks the screw’s head. The helical column of diamond-shaped facets spirals upward.
Twist the shaft or spin the nuts by hand and they slide apart, then draw back together. The dual threads make them travel in opposite directions at once. They come to a stop when they meet, and you can start them moving again with another turn. The facets shift and realign as the nuts travel along the shaft.
It stays on a shelf and gets handled and shifted throughout the day. It draws everyone’s attention as strangers try to figure out the dual threads. Evenings on the couch, it becomes the thing your hands reach for while the story plays on.










