Some simple armouring, and a bucket helm is about the simplest thing to make. The pattern of this one is home drawn, loosely based on the Bolzano helm. There are also commercial versions of this helm on sale
This style of helm is often described as a "Great Helm", but really that's a different pattern. They were a large over-helm, worn over a bascinet and just for jousting.
The finish on this one is a selenium cold-blacking, for that real evil Black Knight look.
I later made a second helm, to a slightly different pattern. This one took me almost exactly a day to make - much quicker than the first! Most of this was because I just cut a cardboard pattern, then followed it - no fiddling round adjusting fit.
Finish on this one was a controlled rusting (by slathering it with a paste of pulverised gherkins, salt and lime pickle), followed by a coat of linseed oil.
Construction should have been easy, with a plasma cutter to hand, but it still took ages. For what was just simple single-axis curling, it was an awkward bit of learning. I don't think I have Matt's talents for creasing.
The cute hat is an armouring cap, normally worn underneath the helm. Looks a bit like a Soviet tank driver's hat if you fasten it. If you don't fasten it, you look like Andy Pandy.