  With the help of google, I have figured out a method to create a low pressure system in a bottle with little to no work. This is to heat up an open container of water and then seal the container. Once this is done, we let the bottle and its contents cool down. By the gas law (pv=nrt), if volume is held constant, and temperature is decreased, the pressure will decrease. Thus, we have a low pressure system above the water. The question is, how much lower will the pressure be. I guess that one way of testing this would be to heat up the water, and then put a filled balloon over the lid. Once the bottle cools, the balloon should have deflated. There should be a way to measure the pressure in the balloon before, and the pressure after. With this method, we could test the change in pressure within our budget (Which is currently $0). Once we get back to school, we should have more access to equipment, and maybe even a pressure guage! Now, once this sealed bottle has cooled, we can stick it back into the microwave (sealed this time), or stick it onto a stove and heat it up.
We can time it until the water boils, and this time should be less than when the bottle is at atmospheric pressure. Hopefully it will be significantly less. Now, our next problem: What type of bottle will withstand losing pressure (without changing volume) and withstand being heated to boiling temperature. I first thought of my urlLink 32 Ounce Lexan Narrow Mouth Nalgene Bottle . This bottle can take all sorts of abuse.
It can easily hold boiling water, be dropped from 30 feet onto rocks, and even take my abuse. My one worry is the lid. I don't know if the lid can stand being heated for long periods of time in the microwave. I really don't want to destroy the lid (or my microwave). Alternatively I could use a jar of some sort, but all the jars I have use metal lids. I think I will e-mail Nalgene and ask them if their lids are microwave safe, after explaining our project. I will let you know how it goes. -Ben Salinas 
