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.
The sketch is built using the P5js library. You can run it by pointing your browser at app.html. That file references an online copy of the file. You can also run it with a local copy of the library; download P5.min.js from the P5js download page, put it in the same directory as hat.js and app.html, and modify app.html to reference it instead of the online version.