This is a bottle cap opener designed in the shape of a piston and also serves as a keychain. I designed it for an engine design competition. I hope you can support me in printing it by liking and downloading this file. I recommend using a 90% infill rate and triangular-shaped infill, and printing it with the materials of your choice. Since it's a bottle cap opener, I suggest using more robust materials. You may need to make some adjustments or sand it down to fit the arm into the piston head.