Here’s a good article for how to build a DIY wort chiller.
Honestly, you can buy these for like $50 at most places – I got mine at homebrewheaven.com (Come on! They’ve got animated gifs on their site!) – and, unless you’re getting your stuff at wholesale, you’re probably going to pay close to $40 for the materials. So, in my mind, it makes more sense to pay the extra $10, save the running around and time spent and have somebody else build your wort chiller for you, but, I know there are good people out there who like to do everything from scratch. Well, this one is for you you sexy little maniacs.
But, regardless of whether you buy it or build it, you’d be remiss not to use a wort chiller to expedite the cooling of the wort so you can move on to aerating and pitching that yeast. Seriously, a wort chiller properly used will cut your cooling time from hours to literally minutes.
Buy one, build one, who cares, but make sure you use one.