I made dolly's out of hardwood. Make it long enough so you can put it sticking upward in a bench vice. Lay the molding over it tapping downward on the molding. A cheap set of punches (or what I use old door hinge pins) can be ground to different shapes. These can be used to put a hard line back in. Also small pic punch to knock out small dents. Block sand lightly and look for low spots. Once the shape is close sand from whatever grit it takes down to 2000. Then polish. I suggest altering the direction of sanding with every grit change. That way you can make sure the scratches from the coarser grit are gone. Cheap to do and time consuming. But the results are worth it. I've done aluminum as well. All self taught. This corner molding was nearly smashed flat. Did all this trim.
Doug