I was surprised nobody ever made a similar device as it seemed relatively simple to make.
But here it is.
I chose to give speeds in pixels per frame (PPF) as it is a value system that doesn't change depending on the fps. To get the speed in frames per seconds, just multiply the obtained value by your fps.
I hope you'll like it. If you find any errors, have any suggestions or any comments, please post them here.
All the electronics parts are made by me and can only be copied giving credits.