Its the fact he went to all the effort to make quarter sized quarters for the quarter sized coin slots
I did see this on one of the facebook sites, he also has a few others, Guy is called Jamie McShan, also has a pacman, a ms pacman, galaga, galaxian and Donkey Kong, all quarter scale, looks the nuts when they are all lined up next to each other
You can find it under Mame arcade cabinet builders on facebook. (Useful if only for the basic plans on how he did the controller)