Tape card stock with a non-blending finish to the worktable. Tape off the areas of the paper that you do not want to paint using a painter's tape. Use an artist knife to cut the tape around small details of the underlying drawing or stamp.
Hook up the Copic airbrush attachment to a small compressor or air can. Insert a medium to dark blue color Copic pen into the attachment.
Spray the card stock in short, quick bursts. The airbrush will allow you to create a tonal effect by moving the brush and the distance of the brush from the surface. Change to a lighter blue brush and spray again. Your paint should be somewhat random on the card.
Paint using a very dark blue. This time concentrate on spraying the edges of the card to be darker than the center. Continue to spray in short bursts to allow the gun to recharge with ink. Allow some of the lighter blue colors to show near the center of the sky. When you are satisfied with the sky color turn off the airbrush and clean your gun with blender solution.
Draw a small circle with your blender small tip on the sky. The blender tip will tend to lift the dark ink. Sketch away from the small circle with small lines to create star-like effects. Add smaller and larger stars where you want them. Color a 1- by 1-inch spot of dark blue ink on your DVD cover. The cover will act like a paint palette.
Drag a light blue tip through the dark blue three or four times and then use the tip to fill in dark areas of the sky. Swirl the tip in circles. The dark paint will come off and blend with both the light blue and the paint already on the card stock. Continue this painting process until you like the way your sky looks.