#DIY
I built sequential shifter by following instructions from @donnycrash8954
Here is the link of his video: • BUILD THIS USB SEQUENTIAL SHIFTER | SIM RA...
You can find more details in a description of his video.
It is built from 3mm thick aluminium (waterjet cut).
I had to improvise a bit with components I used in a build because some parts I could not find in hardware stores here in Serbia, so I ordered a lot from Aliexpress and Arduino code (I've built handbrake as well, so instead of using 2 Arduino Pro Micro boards I used one for both, shifter and handbrake).
If you need links for components from Aliexpress, adjusted Arduino code or anything else, please feel free to ask in a comments below.