http://www.skiptomylou.org/2011/01/0...-bag-patterns/
I made the 1st one..but the last one is a great basic bag. Flattning out the triangle is what makes it flat on the bottom. I have been experimenting with bottoms to make it studier. I am using corrigated plastic now and like it alot. It started life as a for sale sign I found at Lowes or Home Depot. I was able to cut it with a utility knife. It is sturdy and would be easy to clean as its all plastic.