RXBOT is correct - if done properly the new chainplates can be cut from plate material. The edges have to be finished smooth for longevity though, and ideally electropolished.
Did you go to the link posted by Stillraining? Brion Toss is one of the best riggers in the country and his opinion is worth something. He recommends against nicropress except for halyards of 7 x 19 construction, wire not suited for standing rigging. They do not work well on 1 x 19 stainless rigging wire.
Living aboard in Victoria Harbour