You start a touch thicker, 1/8+ maybe 3/16" blank, you contour them to taste on the outside....

Then your final step is to thin them back up from the inside,,,

This is how you achieve the semi-round feel and look with out big chunky scales.... Scales need to be thin enough to still flex...

Gun-stock scales are just that, they are shaped like a rifle-stock it has nothing to do with outside contour...