This is a small P5js sketch that lets you construct patches of aperiodic hat tiles, and displays them along with their associated metatile and supertile outlines. You can download the patches as PNG images or SVG vector illustrations. The mathematical structure of the tile and its tilings is described in the paper "An aperiodic monotile" (Smith, Myers, Kaplan, and Goodman-Strauss, 2023). For more information, including a link to the paper, see my web page about this project.
To run this sketch, you'll need to grab a copy of the P5js library. You can download one of P5.js or P5.min.js from the P5js download page. Put it in the same directory as hat.js and app.html, and point your web browser at app.html.