Hello got my oldest a pre-assembled rocket and launcher today to let him give it a try. I let him carry the engines and accesories to the car and from the car to the spot in the park to be the launch point. Probably not a good idea for a 7 year old but long story short we lost the engine plugs in route so..... Looking for the plugs I found an old red fruit snack in the back seat of my car which I tore a piece off of and formed into a make shift plug, got to say it worked pretty good.