This is a technique shown on a Club Scrap video as part of several ideas you can use carpet tape with. Carpet tape is simply double-sided sticky tape in wider widths, like 2 or 3 inches wide. It can be found in home improvement/hardware stores, or in hardware departments of most department stores.
In this particular style, you stamp the same image on 3 coordinating pieces of cardstock. Then you stack all 3 pieces together and cut them in a good paper trimmer, like a Tonic guillotine trimmer. Shuffle the pieces into 3 sets again, distributing the colors evenly among the 3 sets. Then lay the pieces on the carpet tape to put the stamped image back together again.