MDF: Affordable, paint-ready, but not moisture-resistant. Solid Wood: More durable, stainable, but pricier and can warp. PVC: Best for bathrooms (waterproof).

Caulk: Apply paintable latex caulk and smooth with a damp finger. Shims: Use thin wood shims behind loose moulding before nailing.

Use a miter saw: Set to 45° for standard corners. Coping method: For tight inside corners, cut one piece straight and "cope" the mating piece. Test cuts: Always check fit before nailing.