Step 6- Now you are ready for the last layer. If the center is (color 1) red, you’ll add the (color 2) blue to the outside. If the center is (color 2) blue, you’ll add the (color 1) red. Add the last layer just like the previous steps. Your finished block will measure 4 ˝” x 4 ˝”. Once you have enough blocks, you can start putting it together.