Tried to build a fog chiller. I think the theory is sound, but the execution not so much.
Basically, I took a cardboard box and duct taped in a garbage bag liner. I cut a hole in one end and shoved most of a milk jug in, duct taping it in. On the other end I cut a circular hole, and put a hardware mesh "tube" in. I put all the ice we had in, and taped a piece of garbage bag over the top.
It didn't work that well, but it did have an effect. I found that it was best with the tube in, shoving the fog machine right against the milk jug and angling it down slightly. I had nowhere near enough ice even for the small cardboard box. I also found out that there was a leak somewhere. The effect wasn't that dramatic, but it was noticable.
The current plan is to build a second one, maybe a little bit bigger, inside a foam cooler. Definitely using more ice, either making it and storing it somehow or simply buying a bag or two. My dad suggested dressing it up as a coffin to hide it. That seems like a pretty good idea. I think I'll do it backwards, with the tombstone facing the front of the yard and the fog coming out behind it, near our front door.
The current plan involves two motion sensors, an Arduino, a dropping ghost, lasers, blacklight, hacked camera flash, and some sort of scary sound effect.