I know this isn't an original idea, but it seemed like a good fit for the end of Precal (for juniors: my classes had both juniors/seniors, and seniors needed some time to review for their final, which was two weeks earlier than the juniors'). Here's how my version of a Desmos Art project went this year.
This semester, we studied polynomial, rational, and trigonometric functions. Use these functions (plus any other functions or relations you want) to create an original piece of art using Desmos.
This is an Awesomeness project, which means there are 5 points available. To earn them, make sure your creation:
1. Uses domain and/or range restrictions
2. Uses inequalities for shading
3. Uses all three function types studied this semester.
4. Uses three or more functions or relations not studied this semester and/or not studied in this class.
5. Is awesome! Convince me on the last slide by discussing any struggles you had, anything new you learned, what your creation means to you, etc.
Pretty good results: some kids got into it, and I'm trying to stay positive about things at the end of the year so I won't get into those who didn't (you can probably tell), or those who borrowed a little too heavily from stuff you can find online (or right on the staff picks page, ffs- if you see anything down there that bothers you, please let me know). Some of these are great! The sword and the mosques, the war/peace, the mountain scene: pretty sure all of these were original, and noticed these students putting in some effort.