What's hard to see in the limited set of pictures:

Using a bulkhead mounted rheostat that is accessible on the outside.  This adjusts the speed of the ESC's.

a USB connector to allow connections without taking anything off the gun to the itsy bitsy.

itsy bitsy kill switch toggle.  This is a a toggle switch mounted to the outside to kill power to the itsy bitsy.

there is a fan in the battery compartment to cool the 6v regulator (this provides the brushed dc motor power)  and mtd-01 dc brushed motor controller 

There is another fan on the body facing side of the rear bottom above the ESC's. 

Added a 3d printed nerf rail to mount the lithium ion battery. 

The brushless cage is a 3d printed Regulator cage (same as in my Regulator gun).   This is mounted on a 3d printed plastic shelf that allows me to screw into the shaved mounting holes that the oem cage was using, and then use standoffs to mount to the brushless cage. 

Next to the itsy bitsy inside, there is a 5v switching regulator.  

Next to the 5v regulator, is a small power distribution board that has rails for battery + ground,  5v + ground, and digital high + digital low (for use in the switches)

There are also 4 neopixels mounted inside the barrel with two of them shining directly inside the barrel, the other two provide light that is visible thru the barrel vent holes. 

Initial light scheme is rainbow fading the 10 (5 on each side) that are attached to the fiber optics around the barrel when no triggers are pulled and the dart door is closed.  The 4 inner led's will be solid green.  So if the gun is pointed at you, you'd see green shining out of the barrel. 

With the first trigger pressed, the inner led's go solid yellow. The outside led's will cascade green. 

With the second trigger pressed, the inner led's go solid red.  The outside led's cascade red. 

When the dart door is open, all the led's go solid blue.