I have been trying to track down the origin of this effect for sometime because it is a popular item as you can see by the versions I have here. This is certainly the oldest version I have seen from Mac Made Magic c. 1945. That is Mac with a “c” not a “k” and I think it refers to the first name of the creator. I was unable to find out more info about the creator but this was advertised in most of the major magazines at the time. This version is not particularly elegantly made, but it is as far as I can tell the original and a great effect!
Effect: Here’s a nifty little pocket mind reading effect that will fool anyone not in the secret. Nine blocks are shown, each bearing two different colors. While your back is turned, a spectator arranges the blocks in a row, color to color, and you instantly divine the colors at the ends. May be repeated, and comes out different each time.
(Notice: Includes: Printed Instructions.)( Post Source: martinsmagic.com - click for details )