Help on creating a rube goldberg machine?

Well, me and my group have a physics project to create a rube goldberg machine and we need help on how to create it. It has to last more then a minute and can only be the size of 1m x 1m. We’ve looked at youtube videos and we’ve tried to look at a couple of websites, but we’re still semi stuck. We have an ultimate goal of launching/catapulting a stuffed baby.