Scale
From PyroGuide
A scale is tool used to measure out individual parts of pyrotechnic compositions before they are mixed together. This is done so that the composition has the correct ratio of substances to perform correctly. Compositions should be weighed on a scale (measured by mass) and never judged by volume, as volume is a highly inconsistent measurement for most substances. Digital scales or triple-beam scales are preferred, and both come with a wide range of accuracies and maximum loads. Scales are easily found at postage stores, cooking stores, and online on sites like ebay for very reasonable prices. They are a necessity for any pyrotechnician.
You can also buy a Digital Scale at detectorshop, although this is a Dutch website.