A mold need not be “pretty” as long as it casts cleanly, but sloppy molds will cost more in terms of time and trouble. Do the mold right the first time and it will last through many cycles of casting. After casting in plaster, round off the edges of molds with a sure-form (to prevent small bits of plaster from breaking off and getting in your slip, recycle, etc.). Wipe down molds with vinegar and water (use a 1:1 ratio) to clean off excess mold soap using a soft toothbrush or sponge. Wet and sand your molds all over with at least a 600 grit wet/dry sandpaper. This will make the outside of your molds slicker and simplify clean up of slip dribble