I made the cake tower to hold around 50 cupcakes and a crown cake. It is made of 4 tiers of cake board stacked over soup cans and Styrofoam or thermacol.
What you need:
Styrofoam cylinders and soup cans
Circular cake boards, 2 of each size, 14 inch, 12 inch, 10 inch, and 8 inch
Colored wrapping paper
Hot glue gun and a few glue sticks
First glue 2 similar cake boards together. Wrap them in desired color paper and cover the edges with ribbon.
Arrange them together, and place paper cups to see how many they would hold, then start to work on the design accordingly.
Decorate the soup cans and Styrofoam cylinders with color paper.
I would rather use the soup cans, as they were more sturdy to withstand the weight, but even with hot glue, they dint stick well to to the boards. After trial and error, I alternated Styrofoam and cans as pillars.
Once they are all stacked, they need to sit for a day, then they are good to use.