GNR or ECJS 6 wheeled brake third carriage body for 3D printing in 4mm scale, based on preserved carriage 589 at the Vintage Carriages Trust, Ingrow, Yorkshire, see http://www.vintagecarriagestrust.org/gnr589.htm
Drawn using measurements from the preserved carriage and drawing published in Ken Hoole's book on ECJS carriages. I did this for my own amusement and to make a suitable 3D printed carriage just to display behind a static Kitmaster Stirling 4-2-2, but someone might like to use it who actually models the GNR! With some work in CAD an all third and various other designs could be produced using this as a basis. If you can convert this back to Sketchup and then check it in netfabb or something similar then it can be printed by Shapeways, i-materialise or on your own printer if you have a good one. You'll need to make your own underframe and add partitions, seats and details. Have fun!