Article: If you come across any cracks or chipped ones, set them aside for a different project. Any cracks or chips will make create an uneven painting surface, which will make the shell harder to paint. If you don't have a beach near you, you can always buy shells from an art store. Some florists may sell also shells as vase fillers as well. Rinse them using warm water, and scrub them with an old toothbrush or manicure brush. If the shells are very smelly, leave them in a bleach solution for up to 24 hours. Keep in mind that the bleach may also turn the shells pure white. If you are using store-bought shells, then you don't have to clean them. A simple rinse may be a good idea to get rid of any dust, however. This is not completely necessary, but it will make the surface smoother to paint on. Choose an acrylic paint primer, and paint both sides of the shell. Let each side dry before adding a second coat. Watercolor is easily absorbed into the shell, and will be translucent when it dries. It will "dye" the shell a new color while allowing the shell's original patterns and designs to show through. It is best for solid-color designs and "tie dye" designs. You can also work with liquid water colors. They are more saturated and will give you brighter results. You will need to add a few drops of water to dilute them, however. Acrylic paint is opaque when it dries, and it will completely cover the shell. You will still see the shell's texture, but you won't see its original color or pattern. Acrylic paint is also great for layered designs, but you will need to let each layer dry first before moving onto the next. Choose a brush with fine bristles, such as taklon or sable. Avoid brushes that are made with horsehair or boar bristles, as they will leave behind brush strokes. You should also avoid using bushes that have bent or messed-up bristles. Consider having an assortment of brushes, such as a flat brush and a fine-pointed, round-tipped brush. You can paint just about anything on your shell, from animal faces, to beach scenes, to designs or words. If your scene is very complex, consider practicing it on a sheet or paper first. Having an idea of what you want to paint will lessen the chances of making mistakes later on.

What is a summary?
Gather some shells and inspect them for any cracks and chips. Clean the shells, if necessary. Consider priming the shell if you plan on painting it a solid color. Choose watercolor paint if you want the shell's features to show through. Choose acrylic paint for fine designs, scenery, and solid-color designs. Get a good quality brush. Pick a theme.