This Instructable details how to build a Stirling engine out of a few soda cans, a balloon, and some terminal blocks (and other bits and pieces). Power is provided by tea candles. In the second vid, the builder uses his engine to power a radio.
From MAKE magazine:
In Volume 17, MAKE goes really old school with the Lost Knowledge issue, featuring projects and articles covering the steampunk scene — makers creating their own alternative Victorian world through modified computers, phones, cars, costumes, and other fantastic creations. Projects include an elegant Wimshurst Influence Machine (an electrostatic generator built entirely from Home Depot parts), a Florence Siphon coffee brewer, and a teacup-powered Stirling engine. This special section also covers watchmaking, letterpress printing, the early multimedia art of William Blake, and other wondrous and lost (or fading) pre-20th-century technologies.