I'm a little behind the times and learning curve in using epoxy for filling holes, knots, defects, etc. Been using wood flour & glue and various commercial fillers for this purpose for many years. So, I'm purchasing quarts of West System resin and hardener to start the epoxy journey. I've been working on some projects with walnut and cherry. Question, what products do I use to color the epoxy? Any tips or suggestions appreciated. (Note: I am not building river tables, just filling knots, defects and small repairs.)