here is what you will need
4 20 yard rolls of duct tape
Step 1: Make the Base of Your Backpack
Lay 15 inch duct tape strips sticky side up, overlapping as shown. Once you have laid down about five to six strips (or until 9 inches tall) lay 9 inch strips, sticky side down perpendicular to your previous strips. Now you should have a sheet about 15 in. by 9 in.. Fold over excess tape on the long sides (fig. 3), then trim the short sides to make them neat and tidy. Now you know how to make a duct tape sheet.
Step 2: Make the Under Side of Your Backpack
Now measure the length from your hip to your shoulder to determine the next sheet's length. In my case it was 19 in. So I made a 19in. by 12in. sheet. After you do that connect short the end to the base so that you have about an inch and a half on each side of the base.
Now you want to make a sheet that is 12 in. by 24 in.. then attach the short side to the base again leave and inch and a half on each side of the base.
You should have about an inch and a half of excess tape on each side of the base. Fold these flaps up 90 degrees and then prop up the sides so you can tape the corners, making a shallow box as shown. Once you have done that cut out a piece of cardboard so that it will fit snugly in the bottom of the backpack. Secure the cardboard to the base of the backpack.
Now you need to make another sheet. Yep, another. You should be getting good by now! This sheet should be 8 in. by the measurement of your back from step 2. Mine was 8 inches by 19 inches. Cut the sheet diagonally from corner to corner making 2 triangles. Attach the triangles to the base so that the angles are facing the same way and the medium sides will attach to the under side that you made in step 2. Tape all three sides of both triangles to the backpack.
Now we will make the top flap and the pocket. you will need to make a sheet 12 in. by 8in.. For the pocket lay out three 6 in. pieces of duct tape face up and then lay three more face down on top. Tape down three edges and leave the other one open. Now you can either use Velcro or a duct tape strap to close the pocket the choice is yours.
now cut two strips 8 inches long and lay them face up. then cut two 6 inch pieces and lay them face down as shown and connect them to the flap of the pack to keep it closed. Now for the shoulder straps some people like different lengths for shoulder straps. measure to see what length you like and lay out a a strip of that size face up and lay another one face down. Make two of those and secure to the pack as shown. Then you are done! If you have any questions or comments, post a comment to tell me how to made this instructable better. Thanks and have fun.