My technical brick wall is that I seem to have run out of oommphh with the wee beastie.
This got me thinking about the practical installation in a model of stepper motors as each one needs 6 cables connected to it's little driver board (2 power and 4 motor signal connections)
Even if you mount the Arduino in the middle of a 6 foot model and supply power more locally to the stepper motor that still a lot of cable running inside the hull.
Arduino boards like the Uno ship with lots of goodies on them that most of the time you don't use but as they are often used for prototyping experiments/things it's good to have lots of whistles and bells available.
It's a bit like having a vehicle that's a fire engine, ambulance and police vehicle all in one and you only use it for transporting prisoners back to the nick - all the other stuff doesn't get used.
You can make your own functioning Arduino with just a chip, a resonator and a few simple other components - probably about £5 'ish.
My thoughts are to create an I2C ( simple comms network using 2 wires) network from one MASTER micro controller perhaps the Arduino Mega or Due and then several slaves. The slaves would simply receive instructions from & feedback to the Master and simply control their own stepper - the beauty of this is that an I2C network is made up of just 2 wires. - Sorry for all the waffle
So here is my proposal assuming it can be made to work - it will I think deliver a much easier solution. Picture it this way one controller, a 2 wire network daisy chained to each homemade Aduino controller/stepper motor.
PS an I2C network allows 127 connections or there abouts, you can plug and play in a live circuit etc etc
C-3PO