I saw that the ones on Reusablebags.com were 13 inches x 13 inches and so I made a pattern that was approx 14 inches, knowing that I would stitch around the edge and it would be slightly smaller than that.
I need to cut the edges with pinking shears and apply Velcro but here is what I have
I started off with a newspaper and wrapped 3 slices of bread (it was late and I didn't need a sandwich and wanted to be sure I had ample room but not toooo much) and when I got the shape about right, I measured out 7x7 (because I cut it folded
) on the newspaper and cut. Then I used the folded up pattern on folded up fabric and folded up vinyl (separately) and traced and cut.... This actually worked! (I was thinking I was doomed being so lazy as to not open up the fabric and trace fully or to at least only have ONE fold in it! This was with two folds!)
Hope that helps. Now that I did it, it is simple enough - I just generally don't have the guts to try something without a pattern --- maybe this is the NEW me!