Frames and Mouldings would be pass-through wall mounts for decorative purposes. A 3x3 block to surround windows and doors with a trim in a variety of colors or textures. Included would also be a wall panel for disguising redstone mechanics built into the wall. Mouldings would be for along the top or bottom edge of the wall.
Crests would simply be an addition to the paintings selection for building castles etc.