Substitution Editor is a Java program that allows the user to create rhombic substitution tilings. It is based on this paper in Discrete Mathematics & Theoretical Computer Science.

The tiles are rhombs with angles that are integer multiples of 180/N degrees, where N is an odd number (the selectable values of which are 5, 7, 9, 11, and 13). There are (N – 1)/2 such rhombs, and it is possible to arrange N copies of the one with angles (2,N-2,2,N-2) to form an N-pointed star. For some inflation factors, it is possible to find substitution tilings in which these N-pointed stars actually appear.

Substitution Editor is an open-source project, and the code can be downloaded from the Substitution Editor GitHub repository. There is also a more detailed Substitution Editor homepage hosted at GitHub Pages.