How do you measure out 4 mg? - Answers

You need a very sensitive scale to measure 4mg reliably and consistently. If possible you could make a homogeneous mixture with some inert ingredient and get a larger sample to weigh, making errors less pronounced. I.e. you could mix 1 gram into 999 grams of inert stuff, then measure 400 milligrams of the mixture to get 4 mg of the desired substance. (dilution in a liquid is another means of accomplishing the same thing).