The Traffic Signal Board is a popular magic effect. This model suitable for stage use, working on a different principle, and which can be easily adapted to your individual performing preference.
https://www2.hawaii.edu/%7Ekyschun/balloon/supply.html
Effect
There is a rectangle shaped board that seems like traffic light, and
once the magician hides the board on the back, the green spot moves from
one side to the other side. The magician hides the board again, and then
the green spot changes into red color and goes back to the original
position. At this moment, the audience notices that the back side of the
board is doubtful. However, when the magician flips over the board, a
yellow spot appears on the back side. The magician then flips over the
board again and amazingly three red, yellow and green spots are there!!
Post time: Jan-21-2017