Awesome, awesome project, but for the purist please keep in mind that 8-direction joysticks can be a bit tricky on games that were built for a 4-direction joystick. For example, I popped a convertible 4/8 direction joystick into my home cabinet because Ms. Pac-Man is nearly unplayable with a purely 8-direction stick.
Just a caveat though, this project is definitely a great, inexpensive arcade-at-home solution.
Agreed on the 4-way vs 8-way. Anyone playing Pac Man, Ms Pac Man, Donkey Kong or other classic 4-way games will be very handicapped with an 8-way joystick without a restrictor plate. I've successfully used Ultimarc controllers that are 4/8 switchable using a restrictor plate and the controls are amazing.
Other than that people should be aware that there's no way this runs many arcade games using MAME. I've had desktop computers choke on a lot of arcade games for lack of CPU resources so I can't imagine this plays many games without lag especially since he mentions sluggishness right in the article.
Games like Pac-Man expect the joystick to read Up,Down,Left or Right only.
8-Way joysticks either output combinations of the two directions (Left+Up=Northwest), or totally unique outputs that read as nothing to the 4-way game.
In either situation, gameplay gets clumsy or non-operational when the diagonals are hit. And some people like smoothly rotating the stick from Left to Up, let's say. That would look like Left...Idle...Up to Pac-Man. And that means certain doom if a ghost is behind you.
Just a caveat though, this project is definitely a great, inexpensive arcade-at-home solution.