I think the new WBB 10-wheeler is the sweetest slow-running conventional steamer I know. I have four. This is the third where I have cut down the cab, sand domes and stack height so it will make it under the very low (3.76") tunnel clearance I have on my tight mountain/forest/loggin loop.
While epoxying it back together I decided to add some bits from my parts box along with some extra piping I made from wire and plastic tube, etc. I was inspired by the piping and equipment on the boiler and front of the Lionel Southern Crescent. Apologies to rivet counters and those who care about accurate modeling: I don't know exactly what this stuff is, but like I said, I tried to copy the general look of the Crescent.
I like the result -- more of a complicated-machinery/industrial look from what was a very simple clean and sweet little loco. Painted and lettered it this afternoon. I will weather it tomorrow, once the paint is hardened, into a rather tired old loco that had been modded and added to and is still doing hard service decades after being deemed too old and small for mainline service.
Some of you may recall the Shay I cut down a week or two ago - so it too could go through that tunnel - with the idea of running it almost all the time on that mountain loop. It had binding drive mechanism on O-36 curves and would not run smoothly - that is actually it back around the curve behind this loco in the second photo. THIS loco, once weathered a bit, is its replacement: it runs nearly as slowly.