You can also opt to buy concrete forming tubes, which may be a little cheaper and easier to cut. You'll want to start by gluing together a base, which can be 3-5 pieces wide depending on how much space you have in the room. Add a thick line of Gorilla glue to the inner-side of the PVC pipes and connect them together. You can simply repeat the same process as above and glue each set on top of the other until you are satisfied with the height.
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