My 16" Newt is a pain to collimate.  I need a ladder to reach the secondary mirror screws.  I would like to be able to make on-the-fly colllmation tweaks, with camera installed, from my warm room, like I tweak focus.  I am planning to install a small geared stepper motor (28BYJ) on each of the 3 secondary mirror adjustment screws.  I see two options for the controller.  I could create a duplicate of my MKS Gen L ONSTEP controller and use three focuser configs to run the steppers.  This would require running 12 wires to the steppers.  Or I could build a controller that is small enough to mount on the secondary mirror support along with the steppers (in the shadow of the 4" secondary mirror).  That would only require 2 wires (power) instead of 12.

Or, instead of a second ONSTEP controller, maybe I could use a small CNC controller?

Any thoughts?