I've built and lined several pistol cases from scratch and lining isn't very difficult to do. I use felt purchased at a fabric store and white glue. One important thing is to stretch the felt over the surface being covered. If you use care during the trimming process you'll end up with a good result. Here's a Luger I cased in the "French" style. The felt is a pale gold:
Jim

The 2nd Amendment IS an unalienable right.