I actually helped someone do this before. Started by buying a small fridge for $99 and drilled 2 holes in the side of it for the tubing and then caulked around the holes to seal it. we used a pump we bought at a pet store and had it submerged in water, worked great, except moving your computer even 12 inches is a major chore. Wish I had pictures of that thing
but it was an awfully long time ago.