If you are not content with the locations of your wood or steel studs in an existing wall, you may install a "backer board."
This customer-submitted photo depicts a 3/4" x 11" backer board under his countertop. The backer board gave him the flexibility to attach his corbels wherever he desires. He gave the board's edges the same profile (1/8" radius) as the edges of his Maple Concave 10 Corbels.