Update: February 2010
N Scale: Radio Control
The main part of the N monorail is the only major part that can't be purchased commercially, the chassis. I machine this from a block of ABS.
The motor is a 6mm gearhead motor from Gizmoszone, their GH6122s (about $18). The axles can also be provided by Gizmoszone, 1.5 mm x 20 mm.
The external gears and rear wheel are from a Tyco 440-X2 HO slot car.
The radio receiver is a Plantraco Micro-9, the battery a generic 150 mAH Lithium polymer.
I will post a full parts list soon.

Yes, those are 1/2" squares! The tape on the motor is because it is 6 mm diameter and I only have a 1/4" ballend mill so the slot is 0.35 mm too wide, or about the thickness of a piece of tape.

Sitting on the 5mm wide beam.

It all fits easily inside the shell and runs great!