A lot of my engineering work deals with the combination of mechanical and electrical systems. This involves the use of microcontrollers, sensors, and various other components that require power. I have access to a regulated variable power source at my lab, but I needed something similar to enable prototyping at my home workshop.
Most variable power supplies are quite expensive, but I created a much cheaper option by converting an old ATX computer power supply into my prototyping power supply. ATX power supplies offer several different output voltages (+3.3V, +/-5V, +/-12V) and can withstand heavy loads.