If you know about Peltier modules, a solid-state fridge seems like an easy project. Pump 12V into the module, include a heat sink and a fan. Then you are done, right? According to [Peltier Power], ...
If you need to cool something, the gold standard is using a gas compressor arrangement. Of course, there are definite downsides to that, like weight, power consumption, and vibrations. There are solid ...