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While I've not made anything that involved I've altered screws by chucking them in a drill press and using either a file or a stone to change the shape/size of the head.
Looks like, for those, you'd also have to use a file to make the little cuts/grooves around the outside edge of those screws. If I had something like that it would be a neat project.
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A graver is the tool used to make those marks.
It is a very hard steel tool used to engrave details into metal.
You can make one or buy one.
They often are so hard that chipping of the edge can occur in use so be prepared to soften the graver, touch it up with files, then harden it again.
Even a smaller propane torch should be adequate.
Motor oil is fine for quenching.
Very little tempering is used.