In order to build your own mini fridge, you will need the following supplies: a heatsink, a cardboard box, a petier unit, popsicle sticks, standoffs, an AC adapter, scissors, and on/off switch.
To begin, attach the petier to the heatsink. Cut a hole in the bottom of the cardboard box. Cut the hole the size of the heatsink. Place the heatsink in the box, with the switch facing inside. If you like, you can decorate the cardboard box to look like a refrigerator in advance, by painting it, cutting a door, and using duct tape to reinforce it. Place a piece of scrap metal on top of the heatsink.