A non-slip, nocoat drywall finishing system for finishing inside and outside corners of any angle, the finishing system being a pre-formed, continuously extruded trim piece comprising a semi-rigid member that can be relatively thick in the center and tapers laterally to a thin edge. An outer finishing layer of fibrous material that directly receives paint or texture. A pattern of protrusions, ridges, or grooves on the inner surface of the semi-rigid member to avoid the need for an inner material layer. To install one of the pieces, it is selected from stock and cut to length. A flat coat of mud is applied to both sides of an exterior or interior angle, and the trim piece is placed over the mud and smoothed into place. Once, the piece is in place, the edges are feathered once with a small amount of mud and a wide blade. At that point the corner is complete except for drying.