Screw on cover for empty vanity light sockets.  We still have several of these builder-grade vanity lights in our home.  Modern technology in bulbs lends to not needing all sockets filled with bulbs to reduce the total amount of light and cut down on energy usage.  The empty sockets always bugged me, so I made some blanks to fill them in.  I print them in PETG and with a textured plate.  Gives the fixture a cleaner finished look versus the empty socket.