We’ve covered cheap DIY PCR solutions a couple of times, but there’s always room for one more PCR device. PocketPCR from the wonderful GaudiShop is a $110 PCR kit. The project has a well thought out assembly detailed in this instruction manual, but it will require a tiny bit of soldering.
The USB powered device device has PID temperature control that can reach 99°C. It fits 5 x 0.2ml PCR tubes at once. However, the design requires mineral oil layered on top samples to prevent evaporation. It’s easily the most bang for your buck PCR kit we have encountered so far.
The PocketPCR is open-source, with a GitHub project page, but it isn’t geared towards simple creation of your own device without the kit.