Bumper Material

[JohnBoucher]

It's called Duck Cloth and available at most fabric stores.

[LinuxArchitect]

You can also pick up cotton duck from JoAnn fabric, or whatever local fabric store you have. http://en.wikipedia.org/wiki/Cotton_duck

If sold by number, you want a 5 or 6 weight.

[MrBasse]

We used red and blue canvas from Hobby Lobby. Total cost at $2 a yard put us at $8 plus tax. Same could be found at JoAnn Fabrics or a similar store. We bought the length to run half of our bumpers and just sewed the two pieces together to wrap all the way around. Never had a tear or a failure aside from our awful design for changing colors...