Still another option, particularly for ornate moldings, is polymer. Made of polystyrene or polyurethane, polymer moldings cut and nail as easily as pine. Polymer moldings won't rot, swell or shrink. What's more, many are glued in place and require little nailing. Nicks and dings can be filled with vinyl spackling.
Stainable versions have to be topcoated with a nonpenetrating, heavy-body stain or gel.
If you're going to paint, get the preprimed material and add your own topcoat. Polymer molding typically comes in 12-ft. Manufacturers such as Style-Mark , Focal Point and others offer up to 100 different styles each, from standard crown to decorative panels. Installation takes some practice, though door and window casing is as easy to install as wood. The cost is similar to that of pine for simple molding, but you can save money on elaborate, one-piece profiles.