Prepare a variety of dye colors in plastic containers by adding a few drops of food coloring to a small amount of hot water. A drop of vinegar added to the water will help to set the color.
To dye eggshells, simply immerse them in the water. Leaving the shells in the dye for varying lengths of time will create different shades of color to work with.
Remove shells from dyes and spread them out on paper towels to dry. When shells are dry, gather the different colors in separate containers.
The shell pieces should be arranged in the basic mosaic design before beginning to glue. When satisfied with your design, glue shell pieces into place with white glue. If desired, use a clear spray lacquer to coat the entire mosaic.