Apparently Kylo Ren was almost conceived with the chrome armor:

"The most difficult one [to design] was Kylo Ren. We went through I don’t know how many hundreds and probably thousands of iterations and versions, and one of the great things about that was, the costume for Captain Phasma was designed. That was actually pitched as a Kylo Ren costume originally. For story reasons it didn’t make sense and didn’t work, but we suddenly realized, ‘Oh my God, this is one of the greatest-looking costumes I’ve ever seen.’ And he, then she, became one of my favorite characters in the movie. But the design of Kylo Ren was the most difficult one and when we finally saw the mask and the beginning of that design, it was really instantly clear that was the winner." - J.J. Abrams

Some other concept baddie art:






"Casual Vader"