AL-FI is definitely looking over my shoulder when I'm building the Donkey Boiler.
Based on the drawing, I've estimated the dimensions: height 28 mm and diameter 14 mm. Let's see if this will be a successful attempt:

1: Starting point: a piece of 12 mm beech.
2: Under the fire room door and above the boiler shutter, secured with two bolted clamps.
3: I started cladding the boiler for insulation and safety. I used 1.05 x 0.65 mm slats. This was actually waste from sawing the deck planks. But who saves anything ........

With the example drawing next to it.
I had already blackened the slats themselves with black Schmincke Aero Color Professional. To sand off the fibers once dry before gluing the pieces to the boiler, which then would make it difficult to sand. A pigment ink that I also used a lot on my Bluenose. Because this is thin, I had an idea... wouldn't this be suitable for stoves? I first tried it on the back, which isn't visible. With a result that I'm satisfied with:

I lightened the photo a bit because all the black obscures many details. But fortunately also an unevenness of the parts.

After two coats, it achieved a smooth, matte finish. Ovens that are cherished by the crew and cleaned and maintained from time to time with "stove black." Yes, I remember that from the past. My mother used it to maintain the coal stove in our house. And I remember cleaning the windows with wads of newspaper. That still works very well, by the way.

But that's beside the point .....
Regards, Peter