Okay, don't get any ideas about me now about what I am about to tell you!
Regarding measuring out tiny amounts of dye powder.....several years ago
(lots of years ago) when I was in Greenwich Village in NYC, when 'head
shops' were around, I bought from them an Ohaus scale that measures amounts
as small as .01 grams.  I also remember, (it is so long ago) going to the
Ohaus store (it was in that town at the time) and looking at other
scales.  Don't remember whether they sold them too.  I know this sounds
really funny, but here is another zany idea: if you can find a drug dealer
in your area, I bet you he or she knows about scales of this
type.  FWIW  Anyway, there is a lead for you, nutty as it sounds.  I use it
and am happy with it.  It is not the high tech perfectly calibrating
machine my museum uses, but it works.

Is Ohaus still in business, I don't know, but it might be worth googling.

Best,
Ronnee Barnett