Using an Arduino as a Controiller for a 3D Printed N-Scale Drawbridge

What could be more fun that combining my interests in 3D Printing and micro electronics?  Fun might not be the best word as getting the plastic bits of this project right is currently causing me great frustration ... but it is still fun ... I guess!

The bridge, shown below in an early test print form, is based loosely on the River Rouge Norfolk Southern Railroad Bridge.  It is an Rolling Bascule bridge of the ABT design (though I have no idea what ABT stands for).   This is an early test print and getting all the parts to interact the way they should has been a real challenge.  Only two sections of the drawbridge are shown...the plan is for there to be a total of six sections in the final product.

 Below is a picture of the electronics that will drive the bridge.  The three main bits are the Arduino Nano, the Easy Driver (Stepper), and the Stepper Motors.  The Easy Driver allows for micro stepping of the stepper motors for a smoother raising and lowering of the bridge.

I am a long way from needing all of the functionality that I have planned but here is what I am hoping to do with the Nano:

1. Drive the motors to open and close the bridge.
2. Detect either the open or closed state using a contact switch.
3. Remember the number of steps from the above state to the opposite state.
4. Provide a setup routine to calibrate the number of steps needed for the open/close.
5. Provide a setup routing to calibrate the speed of the above steps.
6. Actuate a relay when power is needed for the stepper motors (rather than power them all the time).
7. Single button operation to cause bridge to change state.
8. Disable switch to prevent operation.
9. Drive 5V signal LEDs (two state) for both the rail and the waterway.
10. Drive two relays for 12v signals.