CounterSync RepRap XY-Plane

DISCLAIMER:
THIS IS JUST THE BEGINNING. DON'T DOWNLOAD ANYTHING YET. IT WON'T MAKE SENSE AND IS ENTIRELY USELESS ON ITS OWN.
-----------------------------------------------------------------------------------------------------------------
this will be a collection of parts i designed and tested that are required to build an XY-plane for 3D printing. here is the basic concept:

4 steppers, one in each corner of a stiff MDF/fiberboard (NOT PARTICLEBOARD OR MELAMINE) at least 15mm thick. there are 2 steppers driving each axis--one running forward and the other in the opposite direction (each axial pair is countersynchronized).

i've considered just about every possible configuration and will post the ones that i think work best and are most versatile.

here's how they vary:
-vertically or horizontally mounted steppers
-above plane or below plane
-right-side up or upside down
-inside rails or outside rails
-aluminum tubing rails + PLA bearings or standard 8mm smooth rod +