No need to throw away the pistachio shells. You can make lots of beautiful crafts like lotus, five or six petal flowers, peacock, Wall hangings , Candle holders, Chandeliers, Medallion/Pendant with Pista (Pistachio) shells.
You simply need to color each of the pistachio shells. Then arrange them like the petals of flowers. These look very colorful and attractive. You can make pistachio flowers in several different colors.
The versatility of pistachio shells as a craft item allows a person using them to explore his /her creativity.