Here’s a simple and clever way to build a motorized cart for kids: power it with two 18V cordless drills. The drills friction-drive the cart’s front wheels via two 3/4-inch sanding drums, and you drive and steer the thing by pulling the drills’ triggers, one with each hand. Two fully charged drill batteries will run the cart for about 45 minutes of play time. Thanks Paul! Link.
The Magnificent Drill Cart