If your home comes with standard 3-inch baseboard molding and you’d like to have a more luxurious trim without having to dispose of your current perfectly-good molding you can simply add a line of cheap ½-inch trim molding two or three inches above your baseboard molding and painting the wall between the two pieces the same color.
Remodeling weblog The House of Smiths came up with this idea when remodeling a bedroom. Use a piece of wood of the desired thickness of the gap to make sure your trim molding is evenly spaced. You can then tape off the top and bottom and paint the entire new molding area; trim, wall, and baseboard the same color. You’ll get the improved aesthetics of tall baseboards at much better price.
Amazing Cheap Faux Baseboard Tutorial | The House of Smiths