I made a bag last night out of a DHL shipping envelope. Best of all it was no sew (yay for staples!). Thought I'd share it with everyone. ^_^
1. Cut off the top of the envelope where the sticky strip is to close the envelope with. Also cut through ONE LAYER of the envelope, taking out about a 3 inch wide strip.
2. Staple the 3 inch strip you just cut out to the top of the envelope. This will be the flap.
3. Next fold the corners so the bag has shape and staple them (in other words, pinch the corners so the side of the bag and the bottom of the bag touch, you should have two triangles that stick out)
4. Staple along the bottom, and a little on the sides so the bag has a squareish shape. You may also choose to staple the corners in the opposite direction so they point down instead of out. Also during this step, take some scraps you have from other parts of the bag and staple these to the sides at the top. Also take additional scraps and make a strap for your bag (mine's about an inch wide)
5. attach the strap with staples and add the velcro (indicated by black squares). I used velcro with a sticky backing, but they're not very durable, I suggest stapling them on in addition.
That's it! Lemme know if anything's confusing!
Here's two other bags I've made out of packing envelopes. Both of which I got when I ordered something from Japan ^_^
This envelope was fairly stiff and formed like a shopping bag. I simply put some cardboard in it to keep it's square shape, added a strap(out of some fabric I had: to hide where I needed to staple it together I made that white thing out of extra envelope material, wrapped it around the strap and stuck some bubble wrap in there), made the decorative cord on the front and added some heavy duty velcro XD
This one was a soft plastic envelope. I added fabric on the sides and tapes around the edges to give the bag a little more weight. I also made a little bubble wrap envelope on the top of the flap. The closure on this one are those little straps, where I made bubble wrap loops they can go through to tie. There's also a back pocket made out of the information slip that was attached there. The strap is made out of fabric wrapped in bubble wrap ^_^
I apoligize for the horrible pictures but my camera phone is as good as I can do! ^_^;;;;