Things You'll Need
Instructions
Select a ball to be Neptune. Any size is allowable, but make sure the ball is undecorated and has a surface that will hold paint.
Paint the entire surface of the ball with blue paint. Due to the methane in Neptune's atmosphere, the principal color of Neptune's clouds are blue.
Use the white paint to draw long, streaky clouds. The white clouds are mostly in the region around Neptune's equator.
Add dark-colored streaks. Slightly darker cloud bands are typical about halfway between the equator and the poles. Do not draw the streaks too dark and do not draw too many of them.
Use the dark-colored paint to draw the Great Dark Spot. The spot should be just below Neptune's equator. Make the spot about twice as long as it is wide. The length should be about one-fifth of the ball's width when you look directly at it.
Add in wispy white clouds around the Great Dark Spot and to the north of the equator. These clouds should be much smaller than the Great Dark Spot and nearly round.