This is my build of a common project, a headphone amp in an Altoids tin. I made this for my cousin’s birthday, so he can practice while maintaining his parents’ sanity.
The tin has holes drilled for a volume knob, on/off switch, LED, headphone jack, and 1/4″ guitar jack.
The amp is powered by a 9V battery via a LM1086 5V regulator, and is based on a LM386 circuit found here.
An unbelievably bright blue LED turns on with the amp, so it doubles as a small flashlight or blinding device.