Working Oscillating Steam Engine MKI

Here is a fully functional, printable, oscillating steam engine.

I started first building a horizontal double action steam engine (you can see it in the background of the video link below,) but while working out some bugs on that one, I decided to knock this one out quickly and post it first.

You can see a video of it in action here http://www.youtube.com/watch?v=BIfqFAG5olU&feature=share

I will call this engine the Mark I, just in case I build an enhanced model down the line.