A way to get a good fit when installing decorative molding is to install the first piece with a square end. Then cut the second piece at a 45-degree angle in a miter box or saw to expose the profile. Use a coping saw and follow the edge of the profile, under-cutting it about 3 degrees. This lets you get a good fit, even if the corner is not perfectly square.
Structural composite panels (the APA tradename is COM-PLY) consist of veneer faces bonded to a wood-base core material, such as OSB. Composite panels are manufactured in three- or five-layer arrangements. A three-layer panel has a wood fiber core and a veneer face and back, while a five-layer panel also has a veneer crossband in the center. When manufactured in a one-step pressing operation, voids in the veneers are filled automatically by the particles or strands as the panel is pressed in the bonding process. Typical composite panel applications include sheathing, siding and industrial applications.