I'm trying to do an experiment for air which I can do at home. What I need is an air pump which can suck in air then expel it into something. I've been looking on amazon for air pumps but obviously just because it says it's an air pump doesn't mean it's going to do what I want. So do you guys know any air pumps that fit my specifications? I'm hoping to buy something really cheap, pretty small and easy to carry.