My parents are both artists who mainly do watercolors AND their birthdays are 4 days apart. They loved this Artist Palette Birthday Cake. After seeing other cakes like it on this site and the web, I found a clip art picture of an artists palette, enlarged it and cut it out.
I baked and stacked two large rectangular cakes. They were just box mixes and store bought icing in between the layers and around. I froze the iced layers for a day, placed the cut-out clip art image on top and carved the shape out. Then I covered the whole thing in white fondant (Wilton pre-made). The hole was tricky but I made it work. I squeezed different colored butter cream icing out of Ziploc bags for the paint blobs.
My daughter’s paintbrushes topped off the cake. It was fun to make and pretty easy!