I got jealous of the nice aluminum door sill plates in my wife's Mini and even my lowly Toyota. So, I decided to one-up:
What's better than aluminum plates? Stainless steel, of course. I had a machine shop laser out plates from 0.7mm bright annealed 316 stainless steel sheet. I then laid down a vinyl mask to cover what I wanted to remain polished. I used 70 grit aluminum oxide to media blast the letters.
I cleaned up the plates and used very thin 3M VHB to attach them to the original plastic sill plates.
I think they look good, but I am a sucker for shiny things. As usual, I made some extra ones (Talon and Eclipse) for anyone interested. See the for sale section about that.