Use the spray paint to paint the cardboard box with the team colors that you wish to represent. For example, if this helmet is going to be a replica of the Dallas Cowboys uniforms, paint the cardboard box silver to match the background color of the Cowboys helmet.
Use the sharpie to draw the team logo on the sides of the helmet. Use stencils to help you trace the drawing instead of trying to make the logo from memory. Fill in the logo with the color of your choice.
Use the scissors to cut an opening in the narrow side of the box. Place the box on your head to make sure that the opening is wide enough you to see through. If it is not use the scissors to cut away more of the box for a wider opening.
Cut a second opening beneath the eyes to represent the bottom of the faceplate on the helmet. You will be able to speak through this opening at the bottom of the helmet.
Place the helmet on your head to try out how it feels. Depending upon the size of the helmet, you may have to use your hands to hold it in place while moving.