Purchase a piece of plywood that is at least 40 inches wide to make a twin headboard or 55 inches wide for a full size headboard. The plywood should be larger than the headboard you intend to create.
Draw the shape of the truck onto the wood freehand or by tracing an enlarged image onto the wood. Pin transfer paper between the image and the plywood, then trace the image with a permanent marker to get your outline. This could be the front grill of the truck, a profile view or any other part.
Lay the plywood on top of the two sawhorses in a secure fashion. Put on your goggles, dust mask and insert your earplugs.
Cut out your truck shape using the jigsaw. Use a blade that is optimal for cutting plywood.
Sand the edges until they're smooth to avoid splinters. Wipe away the dust with a clean, dry cloth.
Primer, then paint the truck to your specifications. Use the child's favorite color or colors on the truck. Allow the paint to dry.
Use sturdy screws and a drill to secure the headboard to the wall. Place the bed in front of the headboard.