Found an amazing custom built but unfinished O Gauge Switcher. I'm wondering if anyone can tell me anything about it.

It's an All-Nation EMD NW2. They were originally made by General Models Corp in the late 1940s in both two and three rail. Yours is two rail, and needs DC power. AC could burn out the motor. If you only have an AC transformer, you can wire in a rectifier to convert the output to DC. It's probably wired up already, since it's two rail DC, all it needs is two wires leading to the motor from each truck.

The shell and sideframes are made from diecast Zamak, not steel.

I have a pair of General Models' original three rail version, which came assembled and painted unlike the two rail version. These preceded Lionel's own NW2, and are far closer to scale than Lionel's.

It looks like yours is unfinished, it needs couplers, a bell, and handrails. The buyer of the kit would be expected to form the handrails himself out of 1/32 brass wire. You're probably missing the handrail stanchions too, which would have been supplied with the kit.

If you look carefully at the area I've circled here on it, you should see where it's marked.

Now those trucks would collect some serious carpet fibers and dirt from running around the Christmas tree back then!

Very interesting I thought it had to be from a kit, I didn't even consider that motor to be DC!  I do have a DC transformer but unfortunately no Two Rail O Scale track and from a brief look on Ebay it doesn't look cheap.  Now that I know what I'm working with this engine is going to be my winter project! Thank you for the information Johnbeere, that was a great help to me! 

This is a locomotive I'd like to add to my collection one day.  With some care and extra details it still rivals some of the better models of this locomotive to this day.  Nice find!