When it comes to milligram scales, you should stay away from the super cheap ones. They are not accurate when getting into the single digits. The one im talking about that costs 55 dollars on amazon is accurate at 2mg and above. Evenly spreading the fentanyl is quite the process. I am confident that it will be evenly dispersed without any hot spots. (don't want to get into the specifics) but, if you are an IV user and know that you will be going through it in a few days, it might behoove you to turn it into a a saline, measured solution. That way, you will be 100 confident on the dose. I will be randomly testing each batch.