Following the instructions on the box of plaster of Paris, mix enough to fill about one-fourth the depth of your pot. (Editor’s tip: The plaster dries quickly, so be ready to pour immediately after mixing.) Center the pipe, socket side up, inside the pot. Rest the fiber disc on the bottom, and pour in the plaster. Use your trowel to spread the plaster evenly in the pot, and allow it to set for at least one hour. You might need to hold the socket centered for a few minutes.