hmmm, the diameter of a pencil is just over a quarter of an inch... I'm thinking to cut up a few pencils, round the edges on a sander, glue to a piece of wood, and voila! (semi)-mass production of queen cell cups! I would mount these onto a square of tin flashing, which would then be secured to the cell bar frame with a dot of molten wax or hot glue. The tin would suspend the queen cell between two frames in the hive or nuc to be (re-)queened.