OK, I have finally sorted out some wood for a core (apple) so its time to make a little progress, and, I have some questions about scrapers. What do you make them out of and how do you cut the teeth, and, finally, I want to go with non-matching grooves but I'm not sure precisely what that means: does that mean that one scraper has 2mm deep triangular teeth at, say, 16 points per inch, while the other scraper has 2mm deep triangular teeth at, for example,10 points per inch?