The Peep Ports were made using small paper cups glued together. I wanted to shape the ports so the inside has a taper, in case the cone packs are not placed dead on. I made a form from 3/4″ plywood and used commercial insulating castable. Each port and plug was made from 2lbs of dry castable and 1 cup of water. Allowed to dry overnight and then the cups were removed and the formed cleaned up with sandpaper and in some cases a dremel. I filled the cups with wet clay to help hold their shape during the casting.