Cut a cardboard or Styrofoam 12-egg carton in half. Use scissors to separate the bottom part of the carton with the egg-shaped holders so each half will include a 2-by-3-holder rectangle. Ensure that each palette will contain six receptacles, enough for nearly every color of the rainbow.
Repurpose cracked or broken ice trays into palettes ready to hold paint. Mix three parts glue, one part water in an old cup. Brush the mixture over the damaged part of the ice tray with a paintbrush. Allow the glue to dry, sealing the cracks to make the ice tray watertight and paint-ready.
Clean out a used plastic frozen dinner container with partitions. Sanitize the container to make sure no food particles or germs lurk in the soon-to-be palettes. Use the large partitions to separate two or three colors of paint for larger, simpler projects.