Here’s a fun idea: if you have a built-in bookcase, paint the exterior wall of the bookcase one bold color, and then paint each interior section of the bookcase a variety of different colors. The colors will create both a focal point and a backdrop for all the goodies on the shelves.
Storage areas are infused with splashes of color for a color blocking theme that pulls the wall color into a mix of shelving backgrounds. There are a lot of colors here, but they balance and complement each other.