Get this precision machined and balanced desk pendulum here:
From Etsy: BUY NOW Double Chaotic Pendulum
Mini Double Pendulum: the intricate dance of chaotic motion from a simple assembly of two physical pendulums (one attached to the end of the other) with the energy of the system moving frenetically back and forth between the potential energy of gravity to the kinetic energy of motion. Chaotic motion (shown here in 240 fps slow motion) is characterized by extreme sensitivity to initial starting conditions, tiny differences in how the system is released leads to dramatically different outcomes each time. This well made precision bearing double pendulum is made by Doug Cvelbar.