What you will need:
Cardboard - lots of it!
Glue - a big bottle of white glue
Something to cut the cardboard - like a box cutter!
A straight-edge or ruler - to help make the cuts straight!
Step 1: Cutting the cardboard
Score the pieces into sections that are8-8-7-7 ribs wide. Fold the cardboard on the scores, roll it up into a roughly equilateral triangle, with the two ends overlapping. (The image below shows a crosssection of what it looked like.) Glue the overlapping sections together and you should have a nice, strong triangular tube of cardboard.