Let's take a look at some techniques that are alternatives and helpful.

As an alternative to using something as a mold you can make yourself some clamps like this.

Make several of them and use them to hold the shape of the tube like you see here. And you don't have to use them alone. You can use them in tandem with your mold.

Another thing you can do to make the tube stronger and to make it look better is to seal the joint where the two edges meet. Do this with a strip cut off the sheet of paper you removed.

Apply glue to it and adhere it right over the seam.

And that's it! There are a whole lot of possibilities available with these cardboard techniques. Here are a couple of things I have made.

Want More Cardboard Projects?

How to Make a Cardboard Catapult

How about making a powerful little catapult out of a piece of cardboard, a pencil and a rubber band. Make a Cardboard Catapult

Make a Cardboard Dollhouse (Tudor Style!)

Make an inexpensive and durable dollhouse that looks great. I give you the designs and blueprints free. And I have a video tutorial showing you how to make it. Make a Cardboard Dollhouse