one side of your toilet paper roll, and fold the notches down, then securely tape them onto the roll.
place your prism inside the toilet paper roll, making sure there is some room left for the beads to move around at the end of the roll.
use your toilet paper roll to trace two circles on your plastic — we used an old take-out container, but any thin plastic will do!
place one of the plastic circles inside the toilet paper roll so that it is covering the prism. you may need to cut this circle down a bit to allow it to fit inside your roll. set the other plastic circle aside.
place 