Hi everyone I am going to tell you  what I did at school. We built stable structures that had to be 25 centimetres tall, had to have a flat top and we got 15 centimetres of blue tack. The people who were in my group were Dawid and Nikolas. The ideas where that we make a pyramid  or a square shape structure. Next time I would like to change my design. You usually need a flat top and pyramids are the best for a stable structure.