Three Potassium Sulfate Crystals

Three potassium sulfate crystal models based on figures and data from a text by AEH Tutton - "Crystallography and Practical Crystal Measurement", AEH Tutton, Macmillan and Co. Ltd, London, 1922, p 114-126. https://books.google.com/books?id=QWpUAAAAMAAJ&
OpenSCAD code is included.