I've used gallons of epoxy for wooden boatbuilding, as well as gluing ebony to stocks. Most folk try and get the joining surfaces too smooth. Epoxy forms a mechanical bond (albeit at a microscopic level). Sawn or coarse sanded surfaces are best. Prime the surfaces with the mixed epoxy before you put in any filler/colouring. Graphite will give you a nice black colour. Epoxy is a handshake reaction (as opposed to a catalytic) meaning you must mix it as exactly as possible and very thoroughly.