How do we buy a Diffuser Panel?

We are currently making a mock up of the field target. We were looking at the plans for the green light that the camera reads and we want to find out what the diffuser panel is made out of, or where we can buy it. If you don’t understand the piece, the number is T07-0202-01. Thank you for your ideas!
Team 2181 Blaine, MN:yikes:

You should have received two of them in the Kit of Parts this year.