Next glue them up and clamp them tight so the glue oozes out between the pieces. Notice the wax paper under the corbels while I'm clamping. This keeps that oozing glue from gluing the corbels to the workbench.
Notice in the photo below you can see how the cleat recess in the back of the corbel came out. This is where I'll use a 2X2 attached to the wall to hold the corbel against the wall. Now I have the corbels roughed out and will finish by sanding them smooth. I have a machine to do this now, but have spent many hours doing it by hand in the past.