Remove the top of your can, then the bottom. Unroll it flat.

For the best effect, adhere highly reflective mirror tape, such as one-way mirror reflective film, to the inside of the can. Bend it gently in half, then bend the halves in half, like so:

Then fold it into a triangle (by crossing two of the ends) and tape up the loose bits.

Tape up an end with translucent tape so that the sticky side faces the interior, throw in your translucent colored beads so they stick to the tape, and then tape up the other end.

Cut a viewing hole.