When I had no digital weighing scale I was relying on measuring cups and spoons to get required amounts for a certain recipe or experiment. One tablespoon of pure water is equivalent to 15 g. However, measuring powdered ingredients are of different matter. One tablespoon sugar is not equivalent to 15 grams. It could be 12 g, higher or lower depending on particle size. To prepare 24 grams, just take two tablespoons. If larger amount is needed, a measuring cup is more appropriate. One cup is equivalent to 191.6 grams. Again the value is maybe higher or lower depending on particle size.
If one tablespoon of sugar is equivalent to 12 grams, we cannot assume that same volume of black pepper weighs the same. The difference in make-up and particle size could be a huge difference in weight per volume.
Even if a weighing scale is around, I find using cups and spoons more convenient and faster in terms of repeated measurements of the same amount.
To calibrate, scoop a full amount of powder. Scrape off excess with a spatula. Weigh on tared digital weighing scale. Record the reading. Repeat three or more times and get the average. Re-calibration is necessary when using other brand.
To make a custom container of desired weight. E.g. 250 g ground coffee. Get a container which can contain more than enough of exact weight. Fill in 250g powder. Place on level and sturdy surface. Tap the container side several times to level the content. Then trim off the extra space. This trick would be useful for manual packaging lines. Every scoop of container means 250 g. A fast scoop, fill to packaging and seal.