I've been thinking about making some one piece scales out of some purpleheart I have in the garage, but I haven't quite figured out how to finish the inside of the scales.

I normally do CA with wood, and I don't think I would be able to use that finishing method with one piece scales.

I've got some wipe on poly, and will be getting some Renaissance Wax. Could I just apply one or the other of these to the inside of the scales?