Instructables!
This week I decided that in keeping with my angsty teenage interest in all things illicit and subversive that I’d learn to open padlocks with a soda can. I’ve seen the instructions floating around the internet before, but took the opportunity to take the time to learn the skill. It turned out to be more difficult than expected, but I eventualy got it to work and am satisfied that in an “emergency” that required a forced entry, (and there were no bolt-cutters lying around) this would do the trick. 
The first step is to cut the top and bottom off a soda can. I did the big arizona iced tea because it gives you more material and thus more chances to screw up and ruin your tool
Next, you flatten out the thin sheet of aluminum and cut off the jagged edges so you end up with a nice looking rectangle.
Measure out a bunch of 1 1/4″ X 2 1/2″ rectangles and cut one (or all of them) out.
Next you divide the square into four quarters, and then make kind of a curved “M” shape in the center of the bottom half. I’ve added some extra lines to make it easier to make the “M” nice.
Cut out the “M” and fold down the top quarter of the sheet.
Fold the flaps on the left and right up and around the part that’s allready folded over. Then, wrap the shim around a bic pen to get it into the shape of the loop on the lock.
It takes quite a bit of fiddling to get the shim to fit in between the rod and the clasp, but it can be done. I had to mangle about five of the shims before I got it. It’s a pretty neat trick though…