I make tote bags for stitchers/quilters. I went to Lowe's and bought an 8'x8' 1/8" plywood sheet and had them cut it into the size pieces I needed for my tote bags (9"x15"). I got 30 bottoms out of that sheet. The sheet of plywood cost me $10. I cover the plywood with a coordinating fabric to go with the bag. That covered bottom is removable for washing the bag. If you want to unstaple the cover you can to wash that cover. If you go to this website - madstitcher.com - and look under accessories then go to The Bag Lady you will see these bags. I took my tote bag with me as my carry on when we went to Hawaii last spring and it fits very nicely under the seat.
Kiki in NC