I saw a similar Spiderman cake on this site and just incorporated a few of my own ideas. I printed a coloring book page of Spiderman’s face for reference and free-handed everything with frosting.
I (bought the Spiderman food coloring set at a craft store) on top of two stacked rectangular cakes. The spiders are large rubber spiders from the party store. My three-year-old son loved it so much.