I start off with a piece of round bar stock that I keep on hand. Square bar stock is fine too. Doesn't matter because I'm practically a pack rat and don't seem to throw away much of anything. I can usually repurpose it here in the gun shop.
I crank up the coal forge and heat up the metal.
Next I use the guillotine tool in the hardy hole of the anvil. I insert the fullering dies so I can create a shoulder of thinner metal to work with. I want to separate the bolt knob from the rest of the bar stock.
Then it's back in the coal forge to reheat the knob. I use my 100 pound Little Giant mechanical hammer and an acorn spring swage to pound the knob into shape.
One last heat to clean up the scale and smooth out the metal. After considerable polishing and some tweaking, the knob is cut free from the bar stock and TIG welded to the bolt handle of the rifle.
It does make for an interesting but unusual bolt action hunting rifle. Something to tread the fields with that's a bit different than the standard cookie cutter guns from the factory.