A 20 × 20-inch sheet of architectural glass rests freely on a banding wheel. Ginsberg lowers a suspended rotary tool fitted with a diamond bit onto the surface and lets go. The bit bounces, skips, and engraves, and each impact pushes the wheel into motion, so the tool making the mark also turns the surface receiving it. Time decides when a drawing is finished: five, ten, or fifteen minutes. From thousands of erratic marks, a circle gradually emerges that no single movement aimed for, produced by rotation, gravity, friction, and vibration.