Ok, all the stuff about smoke generators and the like aren’t going to give you the effect you’re trying to model… You can’t use a “Lionel” smoke generator to depict this:
So save your money…
Now, given that I slept on it a bit, I’ve also given it some thought on how to make the smoke and flame appear to be translucent and still have a shape and form… So, in expounding on the shadowbox example, I’d suggest another course of action, and that’s to use a sheet of glass painted with the smoke and flame and suitably lit from behind, placed behind the model, which is itself lit to eliminate reflections, and to add another one, perhaps just flames, in front of it… I’ll explore that course a bit deeper some other day, but I think it can be done, and fairly easily… I’ll have to experiment a bit before I say exectly how easy…[:D]