Jim Browning makes his own emulsion and has coated it. See his web site for the excellent details that he has posted there for doing this. He now has matrix film made for him at the Efke plant. So, yes, this is a way to go to get custom products.
If your homemade film or paper cracks, add some sorbitol to the mixture. This is a common humectant used in making film and paper to prevent or minimize cracking and crazing.
The biggest problem you will ever have if you make your own film or paper is coating it uniformly enough to make a good quality material. I see a similar discussion going on over on photo.net. Good luck to you all.