As part of a workshop about motor control, the Children's Museum of Houston in the US devised a simplet yet fun robotic device that can draw on spherical objects such as eggs and ping-pong balls via computer control. Once the sphere is locked into the device, a stepper motor can rotate it with another controlling the position of the pen in conjunction with a micro servo.
This is controlled by an Arduino which in turn receives instructions from a PC running some custom software. And thanks to the generosity of the creators, the files for a laser-cut enclosure have been provided so you can make your own without too much effort.
After having the panels cut, this would make a fun weekend project to share with children or just enjoy yourself. To get started, visit the project instructable page. And for more, we're on facebook, twitter and Google+, so follow us for news and product updates as well.
If you're looking into starting with Arduino and motor control - check out our HBRIDGE: DC/stepper motor shield. Based around the powerful Allegro A4954 H-bridge driver IC you can control two DC motors with complete ease, or one bipolar stepper motor. With connections for external power management, a complete beginners' guide and documentation - motor control couldn't be any easier. For more information and to order, visit the HBRIDGE: page.