Homemade ice cream has a unique taste which simply isn't duplicated amongst commercial brands. Add to that the large number of flavors one can make, the sense of accomplishment through all things DIY, and of course enjoying your creation and you have a winner with ice cream made at home.
Warning: It has been brought to my attention that only food grade plastics should be used for a project such as this. For this tutorial, that would basically mean replacing the spindle with something designed for use with food. You can never be too safe- especially if you have kids.
There are really three major parts to this, all of which were found in my home. The most important part is the electric motor which can be salvaged from any number of electronics. This particular one came from a non-working disc drive and the motor was used to open and close the tray. I left the gears attached and just cut the plastic around it so everything stayed intact. Also needed is an empty jar of peanut butter with the lid, and a 100 recordable DVD casing, which needs to be the type where the spindle unscrews from the base as opposed to the type where it is fixed in place. You'll need a few other odds and ends such as a little plastic ring from the stack of recordable DVDs, some cocktail straws, four pieces of short (3-4 inches or so) galvanized wire, and something to secure the motor down later in the process.
Nice what you did with gears, lower gear ratio should provide enough torque to stir the ice cream when it is almost hard.
Here is a nifty battery guide that I just found online : http://www.freewebs.com/dacrochet/Battery_guide.doc
Reference: http://www.webexhibits.org/butter/kitchen.html