PC-7, JB Weld, and others have an "epoxy clay" consistent product in their line. Usually these are filled epoxies that utilize ceramic, steel, silica or other chemically neutral additions that cause the epoxy to be extremely hard when cure. Some advertise that it is possible to drill, and thread into them. All of them I know of are much, much harder than wood. I have heard of Milliput - and should try it because I know it is very popular for use as a wood filler.