Go to Taobao to buy a semiconductor cooling block (15 yuan) and a 12V power supply, with a total value of 30 yuan, and then buy a computer chassis cooling fan with a diameter of 12- 14 cm, you can find a cheap one, as long as 5 yuan; Use the waste aluminum skin on the hot side of semiconductor refrigeration block or go to the market to sell aluminum profiles to find a suitable size to let it dissipate heat; Then install a fan at the cold end to fix it, and a simple small air conditioner will be ready. Note: the direction of the wind fan should be consistent with the direction of the cold side of the semiconductor refrigeration block, which is equivalent to sucking cold air in and blowing it out; If you want to increase power, you can connect more semiconductor refrigeration blocks in parallel. Wish you success!