How to Turn a squirt gun or Nerf gun into a steampunk ray gun with spray paint

Start with a regular plastic toy gun, like a squirt gun or NERF gun. Then, spray paint it a matte black. Once it dries, take several different colors of rub'n'buff and apply with your fingers. Now, you have your own steampunk style ray gun! Or, High Velocity Electrochemical Propellant Device!