well first I would grab a cylinder and pour water about half way and Than i would use the balloon to represent the stomach , i will fill the balloon up with alcohol mixed with water to represent the stomach's acid . Use the mass balance to check the weight of the stomach and how much (food) the person has ate , i could also do this by use the cylinder to check volume without removing any of its props. with one rubber band i would open the the balloon and fold it back on the edge of the cylinder while the alcohol is in it, so you will see water at the bottom than the balloon filled with alcohol over it, when i'm done i will grab the stop watch to time whats about to happen . pickup the 3(100cm*3) conical flasks for a base .
than drop the 3 investigation tablets into the "stomach" balloon start the watch and see what happens.
i hope that this helps. : )