Did a bit of work on my current sallet, since a brow reinforce is one of the things you see on 15th century sallets a lot. Since I now have a large diameter torch, I built a reinforce, rough dished it and then stuck it on the helm to blend in on. Since “hot” steel moves like clay, I used the helm as an oversized planishing stake, with a ball stake on the inside. Here are a few pics showing the series.
Note that I did need to rivet to keep from just pushing the metal around the skull, but the final result got a close blend on the crest of the helm, which is similar to the medieval originals. It will be nicer once I grind and clean up!