Teepee
There are lots of easy teepee projects on the Internet. I used the project from Snip, Burn, Solder, Shred as my starting point. The book suggests using a 4-foot wide canvas drop cloth from Home Depot for the panels, which worked great. It's a nice, soft canvas that's already a good width in one dimension, with finished edges to reduce the amount of sewing needed.
I used a commercial stencil pattern, and regular craft store acrylic paints, to decorate the edges of the fabric.