Work progressing.
The kit is designed as a working model, but I found it difficult not to glue some of the parts that are supposed to move, so gave up and glued it as a static.
The instructions aren't entirely clear on some stages either.

That round chamber on the right hand side isn't a brilliant fit, but I didn't really find how bad a fit until I got to the final stage.
Time for tea and cake. Industrial portions preferred.
End view of the work in progress

Sadly heavy mould line on that upright piece, but I'm hoping it won't detract too much when painted up. After all, cast iron has some mould lines.