Mark,
You said you have worked with wood all your life.
If you use masking tape to poor the 2 epoxy components on, for a perfect 50/50% mixing, that's OK, but then it is difficult to mix them on a flat surface.
I would make a kind of hole into a piece of wood, with the shape of, let's say, one third of a sphere, then after having the right quantities on the piece of masking tape, I would transfer that piece onto the hole, for a better and easier mixing.