holy crap man i just made one of those using your base model but instead of a carb i took a fat pen and hollowed it out then hotglued it into the bottom bottle for the slide holder/downstem like object(red part) then i took a smaller pen that would slide in and out of it easily but allows it to create a seal too! then i melted the end of the smaller pen and forced in a metal bowl and then remelted the plastic pen to it to create the whole slide... it works so damn well it hits like a machine, so smooth becuase of the ice and cold water, hopefully that describes the pic better...

i owe you for that idea

ok the pic is coming later.. damnit