DVD laser carriage plotter parts

Edit: Watch it in action! http://www.youtube.com/watch?v=MO4cYjVboyQ

I'm building a plotter based on two DVD laser carriages. Parts I will print, and eventually some photos of the progress will be shared here. If you're building a similar project, you can use these parts as a base, but you may have to modify them to your needs.

For the pen carriage, I'm using two steel rods taken from another laser unit. I've printed the carriage in PLA, and then drilled the holes to the diameter of the ro