I resorted to building one off an used ATX computer power supply, but voltages fluctuated a lot and also it was pretty high and non-regulable in current output. That was a recipe for troubles. Indeed, when one of the first boards I was learning on caught fire (mis-configured potentiometer + non-limited current dwaw) I didn't feel safe anymore to continue and basically stopped doing that kind of stuff.

So yeah, extremely impressive achievement for a 13 years old student, not downplaying his achievement, but it's wrong to understate the role that his parents and their funding had.