For the monster, see Witch's Experiment.
Fritz the Glassblower is a glassblower found on Entrana. He can teach players how to create molten glass and how to blow glass, providing players with a bucket and glassblowing pipe. He advises on where to find seaweed and sand, the ingredients of molten glass. He will buy molten glass for 20 coins each, but this is not advised as molten glass sells for 613 on the Grand Exchange.
He wrote the book Ultimate Guide to Glassblowing, a guide on blowing glass. He has apparently written other books.