Rainbow cookies, play dough cookies, tie dyed cookies, call them what you'd like...they are FUN to make! Start with your favorite sugar cookie dough recipe. Here is ours. Divide dough into sections and color with food coloring. I like the Wilton's concentrated paste. You can get it at Walmart and Joann's in the craft and cake decorating section for about $1.50 a container. You'll get the most vibrant colors this way. Then divide (cut) each one of those balls into tiny sections. About 3/4" in squares.