I was unable to find a clear backpack I could order in time for an event, but staring at clear plastic online reminded me of something, which I finally realized was the bags in which sheets are sold, which I was reusing to hold extra blankets. A little scrounging around the house and I was able to make a comfy backpack that will be close to waterproof and follows all the rules for event security. And without spending any money...all from materials I already had!
Step 1: Materials
1 thick square plastic sheet bag (if you don't have one, ask someone you know who is old enough to have a "linen closet")
1 detachable strap - steal from a cooler, tote, camera bag, etc. You won't damage it and can put it back later
4 split rings (These are the circles on key chains. Finally something to do with those extra ones in a drawer!)
Something to poke holes with
Step 2: Attaching the Rings
If your rings are not all the same size, don't worry...but use the two largest at the top of the bag.
Install the bottom rings first, by poking a hole through the BOTTOM AND SIDE of the bag. LEAVE the needle.
Slide the ring along the needle until one side of it goes through the same two holes the needle is through. Remove the needle and rotate the ring until it is entirely through both holes. (Like you are putting a key on it)
Repeat on the other side.
Closer to the center at the top of the bag, put the needle and then a ring through the top and back of the bag, just as before. Repeat on the other side with the final ring.
Step 3: Taping the Holes
To keep the plastic from ripping and keep the bag close to waterproof, use thin strips of duct tape on all four sides of each of the 8 holes you made (2 for each ring).
I also covered the original seams of the bag with tape to make it sturdier and more waterproof, as well as stylish!
Step 4: Installing the Strap
Put the strap through the top rings first. If it is thin enough to pass through, that's easier. If not, you can slide it through the rings as you would to put on a key. (That's what I had to do here).
Once the strap is through both top rings, clip it onto the bottom rings.
Step 5: Adjust and You're Done!
Zip the bag, center the strap, and try it on. Adjust the strap to the right length so it is comfortable.
That's it! It won't hold heavy books or all my worldly possessions, but it should be more than adequate for my lunch, poncho, some flyers, phone charger, etc.
And, it cost nothing and the strap can be returned to the original bag the next day!
I ended up making two...