How to build a radar screen prop?

My suggestion would be: 1. For the screen, use a piece of green transparency material, available from a school supply or art supply store. 2. For the rotating display, make a round disk the size of your "radar display" from wood or very stiff cardboard. Cut a small hole in the center to attach it to a shaft, and cut a 1/4" slot from the center to the outside edge. Mount the disk behind the green transparency. 3. Drive the disk at low speed (about 15RPM or so) using an electric motor with its shaft pressed against the outer edge of the disk. 4. Position a lamp behind the disk to simulate the rotating light displayed on the screen.