I went ahead and pulled the trigger on a couple of FM switcher shells via Shapeways and spent some time looking around the site for new products.
This one stood out, mainly for having painted and finished examples! A very nice job on these unique cars. I have always liked the Michigan UP iron ore operations as they were less of a conveyor belt than those in Minnesota. A string of these being pulled by high nose CNW C626s or battered Milwaukee F7s would look great.
http://www.shapeways.com/model/611732/cnw-ore-car-four-pack-n-scale.html?li=productBox-searchThey are also available as a 2-pack.
Note that Shapeways has a 20% promo code on "Black Friday" for orders over $75. I didn't notice until after I ordered.

Best wishes, Dave