you very easily make one. just trace the edge of your stock doorcard, while installed, with a very fine-tipped black marker. remove the stock doorcard. then lay a sheet of some kind of transparent paper over it. (tracing paper, painter's masking paper, or something) trace that outline you made with a marker. then go to any welding supply/ builders supply store and find the section of sheet metal. decide what gauge thickness you want it to be made out of. once you have decided this. buy the sheet of metal. if you choose a gauge that it too thick to cut with a pair of metal snips, then im sure you could take the outline and the sheet metal to any local machine shop and they could easily and cheaply cut it out for you.
just drill small holes and use a flat or beveled head screw to retain the newly fabricated metal doorcard in place.
easy enough man.