This project is featured in chapter 5 of Coding and the Arts.
Demo
Unfortunately because this program uses the camera, it can’t be embedded into the site. You can view it directly in the p5.js editor.
Starter
I highly recommend using a starter projects for students on this one so they can experiment with a working program before trying to customize it. If you like you can just have students build off the demo linked above, or you can use this starter project which places a red oval over your nose.
You can also share the below image with students so they can see the array indices of useful facial features.