The picoReflow is one of the many projects that Apollo-NG is working on in GitHub.
picoReflow will turn a Raspberry Pi into a cheap, universal & web-enabled Reflow Oven Controller. Of course, since it is basically just a robot sensing temperature and controlling environmental agitators (heating/cooling) you can use it as inspiration / basis when you’re in need of a PID based temperature controller for your project.
Off the GitHub page you can also find a link to an extremely detailed resource describing in depth the hole project with plenty to read and many complementary pictures.
Well if you have no need for a oven for silicon based components you can still use this project for a very efficient way of worming up your frozen pizza!