A flexible inside corner trim piece is formed with concave depressions at hinge portions where wings attach to the body. The trim piece can be formed such that wings and a top cap lay flat in plane perpendicular to body or wings and top cap curve at an angle. Hinge portions can be narrow or wide and symmetrical or asymmetrical. The trim piece can be dyed, paintable, or present another decorative surface. The trim piece can include embedded lighting.