I saw these for $20 somewhere online, but did not want to spend that much money on four pieces of card stock with pink squares printed on them. Instead, I took a half an hour and measured out the all the pieces of the pink tower four times onto some pink construction paper. This was easy to do because they are very mathematical. There are 10 cubes ranging in size from 10 cm to 1 cm. Then, I cut them out and rubber cemented them in the patterns I wanted onto 12x18 drawing paper (80 lb). Finally, I "laminated" them using clear contact paper because my laminator can only handle 8 1/2 by 11.
Here are pictures of our four patterns in case you want to do this yourself:
This one seemed to be the easiest, we called it "the Caterpillar"
This seemed to of medium difficulty, we called it "Bunny Ears."
Another medium difficulty extension we called "the Scorpion."
This one was the most difficult, we called it "the Crab."