Be careful, the plastic is hard to cut. Poke a hole in the center of the circle with scissors. Attach them to the corrugated plastic circle with the Scotch brand Mounting Tape. Assemble the clock works into the clock according to the instructions. You can also use regular cardboard and paint it if you can't get corrugated plastic, but it won't be as durable.
Corrugated plastic is made by several manufacturers.
It is known as Stratocore or Coreplast, along with other names. I found that if I purchased it from a signage store it was cheaper as long as I was going to make several projects out of it. More information on Woodsies can be found at Forster's website. Be sure to visit all of our Pokemon Crafts . Otherwise, open it.