This is a " 'Lil Fella" self-refrigerated, six head unit from International Carbonic (http://www.ici.us). It has a 15 lb ice bank (which forms on the cooling coils), and a 1 gallon carbonator reserve.
Some notes on the self-refrigerating feature: The carbonator tank sits in the cold water tank at the top of the unit with the pump, compressor, and radiator underneath. The lines from the syrup run in copper tubing in circles around the carbonator tank (4 passes each) to chill the syrup just before it is dispensed. We love not having to deal with ice.
ya gotta love this footnote: from the link above
Finally, I worry about some people building these machines because of the electrical and suffocation hazards. My machine was improperly grounded and gave me a nasty shock when I stuck my finger in the water. And 13% CO2 in the air will kill a person in just a few minutes. For liability reasons, you should probably include a disclaimer on your site recommending that people NOT do any of this.