how to make a something to ferment in?

i've seen boxes that people have built to keep their fermenting temp. i was wondering if anyone has any instructions on a box i could make to keep my temps cooler. the closet i use can get up to 80 if i don't have my window unit on. then they tend to stay around 72-75. when night falls i usually turn the window unit off.

The other option to consider and the route I'm going in is to just buy a typical igloo type cooler and use ice packs (2 liter soda bottles that you can change out)

http://img.photobucket.com/albums/v405/given2flybrewing/CarboyinIceCube.jpg

Like that.

Also google "son of fermentor" to see different versions people have made.
Here are a few I have bookmarked:
http://sdcollins.home.mindspring.com/FermentationChiller.html
http://suburb.semo.net/jthornton/FermChill.htm

Here's what I'm going to do: buy the thickest rigid pink styrofoam insulation Home Depot carries (like that stuff they put on houses before aluminum siding goes up), and build a little box.
I'm lucky and have an a/c vent right by where I ferment, so the plan is to have a corner over the vent to pump the air in, and then the insulation will act as a mini-fridge for the fermentation days.

So far using thinner rigid foam I already had on hand, I build a 'lean to' over my fermenter with a thick towel for teh roof, and dropped the temp about 5 degrees F.
I figure with a more sealed box shape, with some vent holes on top (since heat rises) I can probably maintain pretty good ale brewing temps.

a 4'x8' sheet of taht thick foam is about $21.

thanks for the help guys! they all look pretty affordable. i love this site.. ha!