Some of the nicer modern cases that I have seen recently (including some from Emebbi) have been lined in a synthetic velour. Looks good and tends not to absorb oil. Available at better fabric stores, but rather expensive. I have also seen lately some very nice wool flannel with a tight nap (similar to very fine men's suit fabric) and it's not too expensive. Lots of shades of tan, khaki, olive, navy.
I would not stretch the fabric over foam, because foam disintegrates and crumbles over time and with exposure to oils. I use cotton or synthetic batting, available from fabric stores or upholstery suppliers.
