You really can’t have too many scales around the shop: a normal bathroom scale for really heavy stuff, a fish scale for medium-weight measurements, and a small scale like this one for gauging mixing measurements and such. And at $10, there’s really no excuse not to have one.
This scale from Harbor Freight is tiny — it measures just 2-7/8″ x 4-15/16″ — and handles weights up to 500 grams. According to HF, it also folds for storage and runs on two AAA batteries.
We use scales like this one primarily for measuring epoxy and plastics mixes when the volumes are too small to measure visually. It’s easy to weigh your cup, then squirt in “X” grams of part A and “X” grams of part B to assure a good mix. Of course, there are dozens of other uses as well.
Digital Pocket Scale [Harbor Freight]