The key tool is a measuring burette which allows you to accurately measure volumes down to a single cubic centimeter. This one is part of a kit from Powerhouse Products. The liquid is isopropyl alcohol (you can use food coloring to make it easier to see, but we found some already dyed green). The squirt bottle is just a cheap water bottle we picked up at a local sporting goods store. Fill the burette to the top, which is the 0 cc mark.