Our first after school class for the 2016-2017 school year will focus on building a mini air-conditioner from a fan and a milk carton. You can read more about the steps involved at the link shown below. Students will opt instead for a 12-volt battery holder with a switch to make the air-conditioner portable. I was able to purchase the following supplies from Amazon: 8 x AA 12v Battery holders with case box wired on/off; Apevia AF58s-BK 80mm 4 pin silent black case fan – connect to power supply.