I worked on a revised version of the minigun a while ago called the Microgun. Basically I swapped the 8 pin Mini Din for a Genesis 2 compatible 9 pin Mini Din. I also changed the power input options to support a 20 pin ATX plug and removed the 3.5mm audio output because I didn't have a use for it. All of these changes made for a smaller footprint than the minigun, hence the name. Since then some improvements have been made to the minigun project so I've gone back through the Microgun file and implemented some of them.
I have increased the spacing of the controller ports, and added a voltmeter option. Another major change is that I have switched the power connector to an 8 pin Mini Fit JR. Consider this power connector to be an extended version of the standard Minigun pinout. It adds an extra +5v pin and, more importantly a power switch pin. The reason for this is to allow you to attach it to an ATX power supply through an adapter cable and still be able to control the power with the built in power switch on the Microgun. If you plug a standard 6 pin Minigun power cable, the built in power switch simply does nothing.
The footprint is incredibly small, just 112.2 x 38.7 mm.
Here's an Oshpark link.
Also for fun I decided to make a fixed resistor version that was as small as physically possible. I call this one the Nanogun, it's basically a cross between the old Minigun Advanced and Standard versions.
This one measures in at an unbelievable 111.1 x 34.3 mm. I honestly doubt anyone could get a supergun any smaller than this without going to a four layer PCB.
Here's an Oshpark link. I still need to add a BOM for these.