I thought about something similar, using either shutter cloth or dark cloth material (Porter's used to sell the latter, but may not any more). Put the black dyed pigskin on the outside with the cloth on the inside, either loose or glued to the leather with something like rubber cement. The shutter material is so flexible that it should have no discernable effect on the flexibility of the lens membrane (bellows).

I guess I can try the leather-cloth combo idea out on the Panoram 4C that I have been using for a repair training aid. It might take a while while I order the stuff to use for practice. As for "originality", since the original felt-leather type material is no longer made, one can at best only go for something that presents the original appearance, but which is also functional.