If this is a flat piece (could be made out of plate) and you have a dxf file, then why not ask someone with a lasercutter or waterjet cutter? Could be a cheap and fast way to have small batch made. Certainly if the holes are the same size or larger than the thickness. If you go metal then maybe it could be made thinner to arrive at that condition. Then inox might even be the cheapest option. (steel is cheaper but will need work or it rusts)