bob2 and Ron H,
First, thanks for the compliments on the ash pan.
Thanks to both of your suggestions, I was able to get one dome shaped today. I used a combination of techniques and I'm very happy with the end result.
Still shaping to match the boiler curvature but will post 'how I did it' pictures when I'm done. Need to finish the flange also.
It's starting to come together...Excited.