Cover the boy's bed with a comforter, duvet or blanket with a large image of a spaceship on it. You want the image of the rocket or shuttle to cover as much of the surface of the bed as possible. You can even buy a blanket with spaceship on it and add the boy's name on it to personalize it. Alternatively, add the name of the space mission or the name of the spaceship to the blanket or comforter.
Paint the entire bed frame a metallic silver color including the headboard, foot board and side boards. If it is a captain's bed and has drawers on the side of the bed, paint the drawers and areas around the drawers the metallic silver to look like a spaceship. Decorate the bed frame with space decals with outer space images.
Make the headboard and foot board look like control panels by painting buttons on them. Use alphabet stencils to paint words on the headboard and foot board such as start, fuel, blast off and ignition. Add knobs and small wheels and used CDs to look like controls.