To answer the OP's question, I'd suggest you use some form of carbon steel that will allow you to harden them once you have made them. The dimensions are given in the drawings but there is no mention of material or hardness. I can copy you the original document if you are interested (PM me).
Apart from needing to set them up carefully and machine them accurately, the basic shapes involved are fairly straightforward. I only made up the mating parts but I imagine a rotary table in the milling machine would be the way to go if you want to make the studs yourself.
I'm sure I've seen these on sale in a few places but not at a particularly appealing price.
Murray