Built one that held four "D" engines once
lmao, oh man, your giving me some good ideas. I remember i bought this rocket off the internet and when i actualy got it, it was about 25cm long. I was pretty pissed off, so i stuck a D rocket in it and never saw it again. Anoher idea you shouldnt try is to launch a rocket that has only one fin on it. The rocket went crazy smashed into the ground skated along the floor at high speeds before smashing into a fence, left everyone watching running for there lifes....but was good fun