The rules are simple. You may use one pad (max) of Post-It notes (or any brand of sticky notes) that are 3x3 inches to create pillars or columns that will hold up weight. No tape, glue, rubber bands or anything else can be used. We typically see competitors engineering pillars that will hold up things like books. There must be at least 3 inches of space between the objects being held up and the surface that the pillars are standing on.