Start with cupcakes needed to serve guests. This will help determine how many "layers" your tower needs. Next collect pretty plates that go with the birthday party them. Place three cups upside down on the plate then surround the cups with cupcakes. Place a second plate on top and cover it with with cupcakes and cups as needed.
Cardboard circles 8",10" and 12", two each for a 3-tiered tower. Glue the circle pairs.Cover soup cans with white paper.Glue the cans and circles alternately placed.Ribbons to cover the sides.
Take a 6 inch by 6 inch piece of 1 inch plywood. Drill a 1/4 inch hole though it with a 1/2 inch wide by 1/4 inch deep counter sink. affix a 1/4 inch diameter by 2 foot long threaded steel rod to the wood with a nut. Then stack.