If you need a wood filler for darker woods like walnut, give your morning coffee grounds a try. First, dry them thoroughly. Then pack them into the crack, knothole or nail hole you want to fill. Soak the coffee with thin-formula cyanoacrylate glue, and spritz it with accelerator to lock it in place. Keep packing in more coffee and glue until the defect is overfilled, and sand it flush. The coffee blends in beautifully with the surrounding wood (as it did for the pinhole knot shown here). Others will never know it isn’t real wood.
– Dale R. Miller