[Scoundreller]

Lifehack: a post office will weigh whatever you want for free. Also many grocery stores have accessible scales.

Best part is they pay for the certifications!

Then there are friends that ahem buy/sell materials in gram quantities. A counted handful of newish coins are a reasonable way of verifying accuracy in those cases. Be sure to weigh different quantities lest the absolute and relative error cancel out.

[Alupis]

The Post Office's scale likely only has ounce resolution, or at best, 0.01 LBS (0.16oz) resolution. ie, you won't notice a couple grams of glue...

[ibz]

Indeed, you need a drug dealer's scale!

[Scoundreller]

A jeweller’s scale!

[Scoundreller]

Ah, they’re all grams here, but that still might not be enough precision on a small device.