Here is my Desmos project.  It illustrates me next to a Christmas tree.  I had the idea to use a sine function as lights on the tree and then rational expressions for the star.  I used a radical function to make a circle for the head and a polynomial function for the mouth.  The arms are both exponential functions and the rest are just straight lines (linear functions).  I initially found it difficult to get the right domain and range and to decide the scale of the functions, however I got used to it after a while and got better as I was doing the project.

https://www.desmos.com/calculator/jpal6xx1fn