A wise man once said, give a kid a peanut butter and jelly sandwich and she'll eat for a day...but give that kid a crazy, motorized, conveyor-belted contraption that makes peanut butter and jelly sandwiches and that day will be a lot more fun! (And yes, that wise man was me.)
Step 1: Self-analysis
Step 2: Get various 110v AC motors
Very important: Make sure that you get motors that go in reverse as well!
(The reason for the AC motors and not DC is because AC is easier in the end, but hey, if you got a bunch-o-DC motors, go to town -- I'm not gonna
stop the creativity on your part.)
Step 3: Make conveyor belt
I also used four 7" paint rollers for the "wheels" and some 1/8" thick aluminum on the sides screwed to a piece of wood to hold them together. Attach one of the 20 or 40rpm motors to one of the outside edges. The whole conveyor belt system should be about 22" long.