Hi, I am Sahas Chitlange , aging 14 , from India . Here's my new innovation on fridge from clay. Its very easy and cheap to build and very cheap. In india the cost is about Rs. 300 only. The project's principle is based on evaporation. you can take this system for camping where you need a fridge to keep your cokes cool. The materials required for making this easy fridge are:
1) Clay pots
2) some sand
For the first time to get the cooling effect you need to wait for 10-12 hrs. The thing you need to remember is adding water after a day.
Step 1: Chose correct pots
You need to chose correct size pots so that they go into each other easily. Prefer new ones because old ones have their pores blocked. This affects cooling.