I intend to convert a $60 toaster-oven into a laboratory-grade chemical reactor/dessicator (or electronic pcb reflow), using less than $500 additional components. I have previously designed a tiny custom mixed-signal ASIC (described in http://www.bifrost-group.com/ee-times-designline-blog-article) that off-loads quite a lot of the controller protection and user-interface housekeeping from a main microcontroller board (such as a Raspberry Pi or TI Launchpad) to an already-designed mezzanine board. That leaves the remainder of functions such as business logic and PID control to the main processor.

The dessicator/reactor will have all the original electronics replaced with a much safer and efficient power supply, relay, and controller and graphic display panel. The main reactor chamber will have complete thermal insulation and high-temp thermocouple installed.