This is a good project for anyone getting into electronics or wanting an idea for something cool. This isn't exactly a "cheap" project but its not very expensive either. The total cost for this project was £16.12 (~$25 at current exchange rate), about the same as a new mini fridge from the shops. If you do not have some of the parts mentioned, you will have to buy them. £38.58 is the total cost for all the materials brand new, but almost half my parts were recycled.The space inside the fridge is 10x10x15, big enough for normal sized cans, large cans, chocolate bars, carton drinks, capri suns(you can fit about 2 or 3), chocolate bars, or anything else you might want. I had some trouble finding a material that was cheap, a good heat insulator, strong, and easy to cut without shattering or being too hard. In the end I got a 50x40x0.3cm sheet of PVC from ebay for £5.98 including P+P. The fridge features an adjustable temperature dial (optional), fan cooled peltier plate, magnetic hinged door, and an LED light that comes on when you open the door.
Note: I never actually finished the fridge past step 5, I still have it lying around in my garage somewhere, but it worked as far as cooling. I wrote the instructable ages ago and as I am unlikely to finish it anytime soon, I decided to publish it as is.
Step 1: Materials
Here is a list of the materials you will need, and the UK prices, and UK places to buy.
-500x400x3mm White PVC sheet - £5.98 - Ebay UK (you can actually use a 400x400 sheet, but I would recommend getting a slightly bigger piece incase you make a mistake and so you can sand each piece)
-White Plastic 3 inch cupboard door handle - £1.29 - Ebay UK
-Small Brass hinges - FREE - found in garage
-Small magnetic sheet - £0.69 - Hobbycraft (any thin magnets will do, but I wouldnt recommend the neodymium ones or you probably wont be able to open the door!)
-Small amount of scrap steel - FREE - I found an old sheet of steel in my garage and cut off some 2cmx1cm strips, and let them soak in white spirit and alcohol to clean them. Anything steel works, you could even cut up an empty coke can if you need to. Make sure it is real steel though and not stainless, because it isn't very magnetic and only contains about 2% iron. Real steel contains about 99% iron which is why it is so magnetic. Iron and nickel are also magnetic so they will work too, but may be harder to find and harder to cut.
-Soft touch 6mm knob - £0.55 - Maplin (optional, recommended if you have a potentiometer for better grip and professional finish. I didn't buy one in the end)
-91.2W 40x40mm Peltier cooling unit - £3.37 - Ebay UK
-Akasa chipset cooling kit - £6.96 - Ebay UK (you can also get them for £10 in maplin. All you need is an active chipset heatsink and a small flat passive chipset heatsink. MY heatsinks were actually recycled and the fan was bought for £2.50 on ebay)
-Sub-miniature lever microswitch - £1.29 - Maplin (optional, for door light. Make sure it is a 3 pin one of a push to break one. This was recycled from an old project)
-5mm 12V white LED - £1.29 - Maplin (optional, for door light. You can also use a lower voltage LED if you have a resistor. I actually got mine on ebay for the same price.)
-Miniature Potentiometer 10K - £0.80 - Maplin (optional, but recommended to control temperature. Any large value potentiometer will do really, it just needs to be able to increase/decrease resistance for the peltier unit. I didn't buy one in the end.)
-Single hole 2.1mm DV power jack - £1.69 - Maplin (or any other DC power jack to match your power supply)
-12V DC power supply - This is not included in the parts/price list since I used a recycled computer power supply. You can use anything as long as it is over about 5V and under 12V. The peltier unit uses 7.6A of power, so remember wattage of peltier unit ÷ power supply voltage = Peltier cell amperage. If it is anything lower than 7.6A (which is probably is) Then the peltier unit won't be running as cool as possible, and this is ok, since we are making a fridge, not a freezer, but make sure it isn't too low. I will show you how to convert an old computer power supply (or new one, it probably works out cheaper)
-Wire - This also isn't on the price list because it is too cheap to measure and all good electronics hobbyists should have plenty of it
-Small amount of double sided tape and thermal compound, or thermal tape - not included on the price list since the amount you will use is unmeasurably small. You just need a teeny squirt of compound and a few strips of tape.
-Hacksaw, coping saw, or wood saw (or if you have one, a jigsaw or band saw)
-Drill (preferably a pillar drill, but a handheld drill will work just as well)
-Files (kind of optional but not if you want smooth edges. Alternatively you can use sandpaper)
-Hot glue gun (to stick it together, you could use a drill and screws or araldite/epoxy)
-Ruler, measuring tape, or large vernier caliper to measure the plastic