The biggest obstacle I had to overcome, is finding a way for the arms to stick. The arms in general were pretty heavy and had to be at a weird angle, which made it hard to secure.
One thing I would like to change is the size of the head. The head is a little too big for the body, and I wanted the robot to be proportional to a real penguin.
Overall, I think this product was successful because my penguin was very big, and was interactive. The first graders enjoyed feeding the penguin and watching the arms move up and down.