Order yourself a Gemini 20 scale and some empty gelatin capsules. Put one capsule one the scale and tare it. Then, put a small amount of your substance in the capsule and weigh. Add more or take some out, until you get your desired dose. The scale is a bit pricey, but it is high quality and will be the only one you ever need.
I recommend getting a Gemini 20 scale. It’s a little pricey, but that’s because it’s accurate and has a quality build. I’ve had mine for 7 or 8 years and have never had any issues.