To create the shims you will need an aluminum drinking can (Plastic bottles also work).Cut off the top and bottom of the can, leaving the middle piece. Make a single cut vertically in the can to create one long piece of aluminum. Cut multiple pieces approx. 2.5″ in width and 1.5 to 1.75″ in height. Then you need to make cuts in each blank to create an "M" looking shape. The mid-point of your "M" can either be rounded or angular. After the "M" shape is cut, simply fold the top quarter in half and fold the legs of the "M" up and around (see photos and video). You can also shape the completed shim around a pen to give it the necessary curvature it will need to slide into the shackle.
To open a lock you need to insert the shim into the space between the padlock body and the shackle, on the side opposite the shackle's locking grove. Once this is inserted, simple turn the shim while working the shackle up and down. This will allow the shackle to almost pull the shim into the locking mechanism as you're turning it. The shim acts as a bypass by moving the locking mechanism out of the way and opening the lock.
Only shim a lock that you own or that you have express permission to pick. Do not use this skill for illegal purposes.