It's starting to get hot in Kyoto, especially upstairs in my house, so my girlfriend has been telling me we should buy an air conditioner, but those are on average $400 to $700 and drink a lot of electricity. I remembered once seeing a DIY air conditioner on reddit once, so today I went to a "home center" and got a few things: a bucket (was looking for a styrofoam cooler but they didn't have any), some PVC elbows, and a small fan. Here's the build:
That's it! Total cost of materials including the fan: about $30! And it will use way less electricity than a regular air conditioner.