Front plate holder?
I bought the one from MillerMbz, it's stamped steel and I presume plated for anti-corrosion. It's pretty nice, although I understand there's also a spacer to get it far enough away from the bumper so the screws don't hit it. I just cut my screws off.
I haven't found a rear plate holder that I like so I came up with a homemade solution. The car had a plastic bracket that only used two screws to hold the plate on, I like to use all four. I had a piece of leftover Trex plastic decking that I cut to size, planed to thickness, and drilled holes in the appropriate places. Works and looks great!
Democracy is two wolves and a lamb voting on what to have for lunch...