Traditional egg tempera yields stunning colors!
Here’s a simple recipe:

Instead of absorbent egg cartons, try small glass jars.
Exotic pigments like lapis lazuli and other crushed gems provide brilliant temperas! I’ve read that the dragon’s blood herb can create a rich deep red, though I haven’t had the chance to try it myself yet.
In rural Spain, I visited an elderly artist couple who are long-time friends of mine. They had painted the interior of their historic residence with egg tempera, creating a subtly luminescent beauty. My designated guestroom featured lapis lazuli tempera on the walls, and I still recall the delicate hues that emerged in the morning light.
Happy painting!