Tired of your fidget spinners ? Use their bearings to build a cool double pendulum !
This contraption demonstrates the theory of chaos which can be said of a system that is extremely sensitive to initial conditions (tje wheather is a good example of this theory as well)
This basicaly means in this case that if you swing the pendulum with a slightly different initial placement of the arms, you will get a completely different pattern !
This build uses 4 standard 608z roller skate bearing (typically used today in hand spinners), a 2020 aluminium extrusion (you can use any 20mm20mm pole that you can find), and a base that fits your needs (mine is a 360200*18mm pine base, the heavier the better).
You will also need washes and screws to prevent the arms from falling of.
The middle part fits between the to arms.
Have fun !
Remember to heat your bed in order to prevent warping while printing the arms.