Got L's Bicycle bucket done before camping a few weeks ago! and since I actually followed the directions this time regarding seam allowance i didn't have to piece anything in!
I would recommend using the heavier interfacing Anna from Noodlehead suggests in the tutorial, or perhaps a heavy stiff duck cloth or something as an inner layer; i used regular midweight interfacing and its a bit saggy but still works!
Little velcro loop holds it to the bar of your bike; perfect for a toy or toy, cup or bottle of water, etc. And not at all a difficult thing to sew!