Article says 4g title says 9mg
Ars A/B tests their titles so I don't know if the submitter editorialized or if they saw a different title than the rest of us, but the text of the article does include building a 9 mg version.
At those length scales the interesting forces at play are not fluid mechanics, but capillary forces and surface tension. It also trivially easy to make - just rip a piece of gold foil weighing 9mg