If you want to make one. You need a potentiometer of the right value and a pedal hooked to a gear, pulley or some other method to turn the pot when you press down on the pedal. Then you need some way to interface the pot to the computer. I made rudder pedals for my flight sim. a couple of years ago. I turned a know into a pulley buy turning a groove in it and the pedals rotated the knob. The interface was thru a game controller plug that plugged into the back of my flight stick. Google it and I'm sure you'll find lots of info.