G
GRapp
I saw best results getting flat scales by hand-sanding them with a large piece of sandpaper on top of a sheet of glass — or other “known flat” surface, like maybe a part of your workbench that isn’t torn up by other uses. Also there’s a technique to it: you wanna go fairly slow so you don’t create a “wave” in the sandpaper because that will just take too much material off the ends of the scales. But you can use pretty coarse sandpaper because that will just help the epoxy adhere better.