Here is an update to the marble roller project. We are using foam board and hot glue for construction. This is a surprisingly strong construction method for prototyping and projects like this.
In the foreground is a new stepper motor. Not sure if we will be using it or not for this project yet.
I got a cool little 4-wire bipolar stepper motor and wanted to drive it via Arduino.
I based the design on this reference:
http://arduino.cc/en/Reference/StepperBipolarCircuit (credit for following image belongs there as well)
Here is how it looks for real. Kind of a mess of wires, but you know what? It works great.