I was bored over winter break and had these parts laying around... so I built her a "Button Box" based around an Arduino. Open source, hackable, and made by hand. This post is just a quick summary ...

But if you can push your button while your yellow LED is lit ... Inside the cool laser-cut box is an Arduino Uno and a 9V battery, plus a current-limiting resistor and the all-important buzzer.

Then, an Arduino board might be exactly what you're looking for. This open-source hardware platform comes in a multitude of versions, from the classic Uno to the ... Out of the box, the Rev3 ...

you can replace them with bigger LEDs or even a light bulb (paired with a relay for the Arduino Uno). Try a toggle switch instead, so you won't have to keep your hands on the push button.