You hold the button down, and it dispenses that drink at a rate of about 0.5 oz 
per second. Total cost was about 2000 dollars. The CO2 canister pressurizes the bottles, and a solenoid valve holds the fluid back. The check valves at the top stop the fluid from dripping when you let go of the button. Code
Video of it in action.

Contact: nulluser || gmail || com