I have had excellent results using a self-adhesive velvet lining, such as that used in jewelry boxes.
You can got to Rockler.com and search for part number 10471 for red, 10489 for green, and 10497 for blue, (other colors will also show up too). Red, Green and blue are their very best colors for cases.
I have done every kind of gun case lining you could think of but this self adhesive stuff really allows for a very clean job, and easy to hide seams. It is about $15 for a 12” x 24” piece.