Latest update. Not much progress, but all in the preparation.....
The boiler came ready rolled. There was a slight flat where the rolling had started and a twist had been imparted, but on the whole the thing looked approximately round. In the absence of any formers I decided to seam solder on the outside, which would be relatively easy to clean up afterwards. Once soldered it was obvious that there is a slight ovality so formers were essential to restore the required roundness.
I used the smokebox front as my reference for the formers. This is intended to fit on the outside of the boiler (as far as I can tell, but the instructions are mute on this point). The advantage of using this is that with careful cutting out the formers will be slightly oversize and can be gently filed back until a good fit.
The metal used was nickel silver etch waste from the chassis of an Oakville Black 5 (Mickoo would never allow that amount of metal to go to waste on an etch!) and the other cut from a piece of thickish brass I had in stock. I followed the normal procedure for marking out, using an indelible marker which showed the scribed line. I also marked off the discs in quarters so that I had references to work to as I rotated the pieces during filing back to fit the boiler barrel.
Both discs are a decent tight fit and have restored the boiler to it's proper profile. I'll take the centre out of the disc at the firebox end so that I can fit a speaker, gain access for seaming the boiler on the inside and to give access for adding any weight which may be desirable.
Some more metal was cut from the sheet in preparation for making the firebox formers. Again, none are provided in the kit and I can only assume that forming this rather complex shape is intended to be done around thin air. I used a scrawker to cut the metal as I find that gives me a nice straight line and no problems with the metal bending as it does if cut with tin snips. Both pieces of metal were polished and sweated together so that I could cut two out for the price of one.
I cut out the firebox shape from the scaled drawing and stuck this to the metal using mounting adhesive. Unfortunately, despite leaving for the requisite ten minutes before starting cutting the drawing shifted on the brass, which accounts for the strange cut at top right. Fortunately I realised before I'd cut too far, and as these are simply formers it wasn't too painful. Here the completed formers are laid on the drawing.
And duly separated with the aid of a gas torch. They appear slightly asymmetric here, but when laid on one another are a pretty good match.
Here's one of the formers laying on the firebox to be formed.
And here, in an approximate position within the frames confirming that, at least, the overall width is pretty good. In fact, allowing for the thickness of the firebox wrapper they may need a small amount of filing back so that the unit can be made to fit.
Now to do battle with the firebox.......
Brian