Bone is best, if you haven't done your homework about the rest. There's Corian, which is rock dust inbedded in acrylic. Can be had for free from the dumpster of kitchen counter fabrication shops. Or you can buy sample pieces. Down-side is that you have to cut and mill it down to nut/saddle blank size. Not easy for an average musician to do, who doesn't have any wood-working or machinist experien
