From Eric @ MPD1:
We purchased a 3 pc set of grilles from Rick Bottom, these are custom made by Carriage Works for him. The lower grill is meant to be an overlay but we were having none of that.
1st step was to make a flange for the grill surround so we had something to attach to. This pic is the fiberglass laid up on an old bumper cover.
Here is the part removed
Here it is trimmed and ground smooth!