This project requires a CO2 system - making it the perfect add-on project for someone already outfitted with a kegerator.
Dispense shots like a madman, mix drinks while you are dispensing them, or even use it for (gasp) actual soda dispensing.
This project is very, very easy - so easy, in fact, that it should probably be regulated by your state's Liquor Control Board.
Step 1: Acquire a SODA FOUNTAIN PRO
Step 2: Buy the plumbing fittings to connect this to a kegerator
Plus, the goal is to have a bar gun - and the bartenders out at real bars don't have time to pump. So, it was clear that CO2 was the best option for driving the pump on a continous basis.
So, in order to hook up the gun to a CO2 system, you'll need the appropriate plumbing fittings to connect the small tube to the standard size CO2 air system.
I did this by purchasing a 1/4" hose barb to 1/4" female adapter and a 1/8" inch hose bard to 1/4" male plug. Cover the male fitting in teflon tape and screw it together.
Don't forget the teflon tape - it will ensure a good seal between the fittings and costs less than the CO2 gas you'd otherwise lose.
Cost for this whole lot at a respectable hardware store should run about $5-$6.