I bought a canvas dropcloth from the local hardware store that was almost twice the required size (yes, I briefly thought I could make two puppet theatres!) and was pleased with myself as it seemed a cheap way to get a huge piece of cloth.....
but no.
The dropcloth was pieced from about 5 smaller bits and had ugly seams all over it and no one piece was big enough for the theatre background. It also had a great big stencilled logo on a corner which was not visible from the outside packaging.
Luckily spotlight had a sale and I bought some cotton canvas. Now if only I was inclined to do some painting I've got a dropcloth....