I received my 16mm scale (1:19) Puffing Billy underframes by GVROCKSNOW today. These are the Version 2 with the 1mm section thickness. They are 400 mm long and 100mm wide and they are superb! All the detail printed beautifully. The truss rods and piping are delicate, but that said they are close to scale thickness which I like. The actual frame is very strong due to the interconnected channel construction, despite the minimum section thickness and light weight. They were well packed by Shapeways (a huge box with gallons of foam) and all arrived in as printed condition.
All eight are excellent reproductions. There is no way any other cottage production method short of styrene injection moulding could achieve this level of detail and the C channels could be tricky even for this. I was going to polyurethane cast from a master I made (without the C channels), but my efforts can't match these models.
Accucraft AP11-738 knuckle couplers fit the frame openings for the couplers well and the Cambrian models Fox bogies also work well with them.
They are expensive though. It would be great if the cost per underframe could be brought under the $100 mark.
More Shapeways VR narrow gauge wagon bodies to fit these underframes in 16mm scale would be great of course. Otherwise I shall have to start building bodies for them for which they will provide an incredibly detailed platform.