If you're looking to make your own tension wrench, there are a few things you'll need to gather first. For the body of the wrench, you'll need a small piece of metal or sturdy plastic. The size will depend on the lock you're trying to open, but for most standard locks, a 3-4 inch strip should suffice. You'll also need two small screws and some strong glue.
Once you have your materials, start by making a U-shape out of the metal or plastic strip. This will be the part of the wrench that applies pressure to the pins in the lock. Next, take one of the screws and attach it to one end of the U-shape so that it sticks out at a 90 degree angle. Doing this on both ends will create handles for you to grip when using the tension wrench.
Now it's time to test it out! Insert the business end of your new tension wrench into the keyway of your chosen lock and apply pressure with both hands while turning slowly. If everything is working properly, you should feel resistance as each pin lines up and falls into place. With a little practice, picking locks will be a breeze!