This paper describes computer programs I wrote to assist with the design and fabrication of two quilts based on geometric tessellations of the plane. Aside from creating and refining the overall compositions, the programs also produced printable templates for paper piecing, and in one case, created a detailed assembly plan. The software enabled me, as a newcomer to quilting, to successfully fabricate designs based on complex tilings with seams that are not constrained to meet at 90° or 45° angles.