So, if I want to make my own heatsinks, and make them very slim, then what's wrong with making them non-finned, but a spiral tubular channel, for coolant/water to pass though? Like a car radiator, but without the fins. More like the water jacket (condensor) of a distillation still. I would use a thin copper/aluminum tube wrapped around the aluminium feeding tube (isn't that like a nasogastric tube?), and then the coolant can pump through, to keep it cool. With the addition of potential Peltier devices to cool the fluid elsewhere.
Or even, just mount 3 or 4 slim Peltiers to the feeding tube, and use a square feeding tube for 4 Peltiers.

Thanks.
-Joshua (Dodgy)