I discovered a wonderful new way to cast !! I purchased some 16mm plastic test tubes (CHEAP) I then take my brass tube and plug each end with foam ear plugs. Now, here is the easy part.......mix you casting resin and pour in enough to measure about 1 inch - then, slide in your brass tube.....The force will make the resin glide up and around your tube. Pour about another inch on top of tube and let harden. Tubes will come out easily.