A very fine example in clockwork was built by Drew Donaldson for shunting on his system. Thankfully immortalised in print - and in a case at Cultra. At least Bob painted his the right colour unlike Drew’s CIE green! Text from Gauge O Guild archive. The article is revealing both as to Drew’s methods and his writing style.
Have you tried Laurie Griffin or ScaleFactor, Alan ? They may have a pattern part. Smallbrook Studios do similar chimneys on their NG kits, and may be able to help.
Time to pack up the bench for moving house - and time to reflect on 8 years of modelling here. We moved in and I brought my collection of Japanese N gauge plug and play with me. About 2016 I made a plastic O gauge kit - which wobbled on 3 wheels - and bought a few RTR locos and stock. Eventually I plucked up the courage to try a brass kit. Which I managed to snap in two by over bending it - but still made a working wagon by the end. And eventually jumped from 4’8 to 5’3. Never in a million years did I think I’d have two Sligo engines at the end of it all. Thanks for all the support thus far. Looking forward to the next adventure !