You can buy dehydrated urine and mix it back up to make it when you need it. The process would be similar to this but I am not sure as to the details because it seems you need to evaporate it quick enough that the urine doesn't decompose into by products that can be tested. But, on the other hand, I am not sure if you heat it up too much if it will cause any breakdowns that can be tested for either. It seeems there has to be a balance somewhere.

On the other hand, urine can be frozen for a year or kept in the frig for a couple of weeks.
FakeBoobsRule Reviewed by FakeBoobsRule on . does this work? Could someone please tell me if this is true i read it on a website a while back and it soundss like it could work: When you are clean piss into a jar and then let your piss evaporate. Then chip the residue off the side of the jar. If you add water to the powder that you get it will be the same as urine. if anybody has ever done this could you please tell me if it works? Rating: 5