I made an inexpensive and accurate grain scale to use in my homebrewery. It is the old Balance type scale, a suspended rod with a bucket on one side and lead weights on the other.
0 | ======A====|===|===|===|===|===|===|= /\ S S S S S S S / \ _ ------ [_] | | | | | | ------Well, That thing (<-) is a bucket, and the little thing hanging from the S hook is a 1 lb lead weight I got at the fishing tackle shop. I also have a 2 lb weight. I checked them for accuracy on the gram balance here at the Lab, but could also have taken them to a grocery store to weigh on their certified scales. To use the grain balance, its just a matter of measuring carefully to set the distances, add the appropriate amount of lead weight to the moment arm and add or subtract grain to make it balance. It can be Very accurate. I used standard galvanized steel electrical conduit for the rod. Works great.