I eventually got around to modifying the CAD model to increase the size of the rubbers. Output the STL file, and back from Modelu came the first 'production' batch of springs and axle boxes.

There was a tiny bit of fettling to fit them to the brake van model. The axle box and springs were modelled to exact prototype dimensions. Well, as exact as the original LMS drawings - who knows what adjustments or liberties were taken in the real world of 1920' - 1930's manufacturing? I wouldn't be surprised if there were some compromises in the design of the brake van etch either. Anyway, they fitted easily enough and, to me, they look the part. They'll look less startling when painted.

Overall a most interesting and productive exercise. Very happy with the end result. And thanks to Alan at Modelu for making the technology accessible to all of us.

I'll be doing more of this, and probably the next project will be to model up a family of typical BR wagon axleboxes. It is usually assumed that they all look a bit like the split cast steel RCH oil 'box. There are some different types, some very different and some subtly different.
There are at least two variants of the classic split cast steel box with slightly different casting shapes. There is a split cast steel type with distinctive weight relieving (I guess?) recesses cast into the spring seat. The common and ugly fabricated square box type with flat front cover. A boxy looking cast steel version with a pressed front cover. And just for fun I fancy a front cover 'box with the cover hanging open and exposing the axle end. And that's just for the 'standard' 12, 13, 16 ton stock. There's heavy duty and special axleboxes. And then the varieties of leaf spring to match. Combined with the Rumney underframes and some kit bashed Parkside bodies there's not much BR common wagon stock that can't be accurately represented now.

Then some of the LMS hardware. Some choice Midland springs and axleboxes. There are a few LNER 'boxes that would be nice to have. The GWR seems to be well served by the trade already, and anyway the Swindon design language always seems a bit mean spirited and Edwardian to me, but that's just my engineering neurosis. 4mm and 7mm. You could do some cracking stuff in 7mm this way. Dream on... there's already a huge list of projects to get stuck into.