There are lots of ways in which the balloon manufacturer will be able to know who are their other customers apart from those who purchase as stock in the party stores. They could do some research as to what other occasions are balloons useful for. This could be for the school fair as decors or used in the experiment, and many others.
They could also do surveys and other stuffs. By knowing what other purposes the balloons may have, they can design and manufacture the balloons accordingly with the proper material.
