I went to the hardware store and purchased

25'	1/4" copper refrigerator tubing
50'	3/8" copper refrigerator tubing
12'	3/8" Clear plastic tubing
2'	1.5" Pipe (used as a form, then discarded)
2'	3" ABS plastic pipe (used as a form, then discarded)
2'	6" Sheetmetal ductwork pipe
4	Pipeclamps for the 3/8" Clear plastic tubing
1	small submersible pump (80 gal/hour)

I used the 1.5 inch pipe as a form to wrap the 1/4" tubing around till the whole 25" was coiled around the 2 foot pipe. Then I did the same with the 3" pipe and the 3/8" tubing. Then I pulled out the pipes and I had two coils, one about 1.5 inches and the second about 3" around and about 2 feet long (I streached the coils a little bit). I put the small one inside the large one and hooked them together with a 3 inch section of the clear tube and some clamps. I then took the rest of the clear tube and cut it in half and connected one to the pump and one end of the coil and the other to the remaining end of the coil.

Finally, I put the coils into the 5" sheetmetal ductwork pipe and the pump into an ice chest full of ice and water and plugged it in. Within seconds, the copper coils went down to about 35 degrees as the water pumped thru them.

The pump was about US$40, but everything else (except the ice chest) I got for about US$30.