Cut down the length of the remainder of the tube, annealed flattened, cut into two circles, 9mm larger than boiler tube. The wooden plug used on lathe when scoring, was reduced by twice thickness of copper +. A bolt fitted in the centre, this will be former for end plates. I know it should be steel, but I don't have any. I have used ply for this before with no problems. Annealed plates again, started the flange. Annealed again now in the citric acid, for next time, slowly, slowly catch monkey.