For portability, the unit is desired to be small, battery operated, ease of operation, and hang-able by it own cables without long term damage, and low cost.  To help meet the goals the unit includes a display to indicate the relative  stepper position since the unit was turned on.  The will be powered from either NiMH or Li-ion batteries.  Whichever I have that fits in my  on-hand inventory.  To keep size and cost low, the enclosure will be from a re-purposed wall charger.