Science Buddies: "Ask an Expert"

My son wants to build a useless machine from legos for his science fair project. The problem is he is supposed to have an experiment in mind which he creates a hypothesis. I cannot think of a good experiment that would support building a "useless machine" any help you could give would be appreciated!

It's always the best to have the machine do something that you can collect data from. But if nothing can be done about that, perhaps you can try experiments concerning buoyancy or volume. Or you can try to introduce a third idea into the experiment, like by coating the machine in different liquids and seeing how it reacts to heat. Another idea is seeing if you can build the machine in different ways to make it harder to break by dropping it, or something similar. I hope I've helped a little and given you a few ideas.

I should have been more specific the "useless machine" is the machine that is designed to turn itself off immediately after you turn it on. It is useless but entertaining and my son is fascinated by them and wants to build on with his mindstorm kit however I can't figure out how he can do it within the parameters of the science fair.