The thing I'm really worried about is making each chip as physically identical as the next. I don't want to be able to know which rune is which by shape, size, or thickness; I'm afraid I'd start to "cheat" in my readings, even if only subconsciously.
G - I kind of wandered about that as well. I'm not sure I can make them the same width. I have ash in my yard too. When you finish your runes, I'd love to see a pic of them.