I've revised this model significantly, and now I've finally started buying the parts to build it.
The boiler is now actually round, instead of an approximation of a circle using cheese slopes. It slopes down at the top slightly, a technique I borrowed from
Andrew Harvey and
Britishbricks.
Another big change is that the cylinders are now made using
3x2 plates with hole instead of the much rarer and more expensive
black Technic cam.
The tender is now 7 wide at its widest, instead of being mostly 7 wide, with an 8-wide section around the top.
The average price per part for this is higher by a country mile than anything else I've ever built. Aside from the wheels, there are several quite rare parts including the
windows at the sides of the cab, a
1x2 1x4 dark red bracket, dark red plates with door rails, dark red macaroni bricks, dark red rigid hoses, and worst of all the
dark red half cylinders in the boiler. It's certainly made me think about my colour choices for future train MOCs!
Hopefully I'll be able to start building in the next couple of weeks, when my Bricklink orders have all arrived. I'll post work in progress shots when the time comes, but for now, here's a prototype of the sloped boiler: