I use all kinds of different materials, it depends on the customer/knife design,what's in my head to try. My favorite though is stabilized,spalted woods. Stabilizing lets you use some incredibly fancy burls that would normally be way too weak to normally put on a knife. The acrylics that are injected into the woods(I think that's how its done) prevent shrinking, warping, waterproof the handle and impart a permanant finish that polishes up beautifully. I also like regular woods, three of my four personal knives are handled in walnut, briar root and black mesquite, but lot of my customers don't want it cause they think it'll dent too easily. I also use an awful lot of Micarta. I like it and my customers do cause it's both good looking and tough as nails; stuff's impervious to just about everything.
I do use dymondwood occasionaly, some of the colors are ok, and it polishes well. Used to use Sambar stag when it was available, and have used a fair amount of well dried Whitetail horn, though I think its too weak for a hard use knife. Also like a material called Poly Pearl on certain knives. Use reconstitued stone as spacers fairly often, usually turquoise or malachite, in fact the one blade that I'm building for a customer now has a recon stone spacer and stabilized buckeye burl scales that I got from Frank Jacobs, who posts here. This guy is a hunter, by the way, not a collector. He's also a stockmaker who know's wood and want's something out of the ordinary. The materials I stay away from are those that are either endangered or used strictly for collector knives. That includes ivory, fossil ivories/bone, and most rainforest/tropical woods. I do use some of the woods if i can be certain they come from sustainable sources. Most rosewood, for instance is plantation grown. And so on.
