These are pouring spouts, they are glued (using the clay slurry) to the tops of molds to enable over-filling with clay slip (since the slip level drops during the time it is left in the mold). The "pouring spout" function permits much easier cleanup. Before each use I immerse these in water for a minute to remove the dried-on clay from the previous cast. But, obviously, that needs to be cold water.
Standard 3D printing technology (not printing with clay itself) is very useful to potters and ceramic industry in making objects that assist and enable production.
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