From scratch, with pieces from here and there. I used a handbrake for racing car simulators, an accelerator for electric bike, spings, shock, switches....
The most interesting thing has been working with Arduino and the Hall effect sensors. I had never worked with them and it has been quite interesting. Thinking about this, I have to get stronger magnets since I have some noise in the signal from one of them and although it is hardly noticeable on windows, I want to reduce it to the minimum.