A faceted diamond-patterned column sits above two toroidal nut rings resting on a tall threaded shaft. The shaft carries two threads, so when you twist it the two nuts travel along in opposite directions at once. The column is capped by a flat disc with a slightly wavy, scalloped edge.
Spin the nuts along the shaft and watch them move back and forth. The bolt head has a jagged star-like gear edge you can grip, and each of the three stacked cylindrical discs below the column carries fine concentric lines circling its side. The nuts travel along those helix threads until they meet at the same point and stop.
The movement is hypnotic.









