This is a plain resize from 2mm:1ft to 6.35mm:1ft of my GWR O30 wagon, without wheels, and I have done it because someone requested that I look into offering one of my models at this scale. Of course the overscaled details for emphasis and printability in 2mm:1ft will be overscale in the larger scale too. On the other hand it may make them more robust or mean they will be printable in a lower resolution material than frosted detail plastic, so saving on price. You will need your own wheels to complete the model, and couplings, cosmetic coupling hooks, and brake levers. The pinpoints of the conical recessions for the ends of the axles are about 31mm apart in the design. I suggest drilling deeper or packing with adhesive to take a metal bearing for whatever metal axles you are going to use. I know almost nothing about modelling in this scale, but I gather the running gear dimensions vary between different manufacturers of RTR products and there is a history of more than a century of on-off compatibility between them. I may have to tune this model to specific wheelset dimensions supplied by the prospective purchaser, so please share this information with me so that I can check it for you before you buy.
For a little about the history of the real O30 wagons, please see the notes on my 2mm:1ft model, and of course the usual reference books.
Because of the cost in the material I expect will be the best in the end (Frosted Ultra Detail) I am wary of offering this experimental model for general sale. I would prefer any prospective purchaser to get in touch with me first to discuss how they plan to finish the model.
UPDATE 21st August 2016. I have increased clearance beneath the floor and moved out the inner faces of the W-rons to accept wheelsets described below. I also took the opportunity to thicken the W irons slightly. The wheelsets I have designed around are 45.49 mm over axle points, 26.47 mm back to back, 38.12 mm over wheel outside faces, with flange diameter 23.00 mm and tyre diameter varying between 16.0 mm at the outside face and 17.2 mm at the base of the flange which is about 0.7mm thick at that diameter. These dimensions were supplied to me by the requestor of the model and are hopefully typical but there are probably various designs.