The square beads are made of etched bi-metal.Bi-metal is made by fusing a layer of copper to a layer of silver.The artist created design is applied as a resist to the copper and then etched, thus revealing the silver. This is done while metal is flat. It is then die pressed and formed to make a sliding bead. The copper is then oxidized to a black-brown patina. These beads also spin and can be very entertaining is a boring meeting. Variations on this design are avaiable.