Can't afford a Glace-A-Tron 6000? Or a Cuisinart ice cream maker? Or the neato ice cream making balls that shuna mentioned?
How about two plastic baggies? kidsdomain.com gives a guide to making ice cream in plastic bags. Put ingredients in small baggie. Put ice and salt and small baggie into large baggie. Shake, shake, shake.
via boing boing
