This is a teaching aid that was designed to be used to teach students early in their engineering college career or high school students in a engineering-fundamentals class about moments. Moments are a very import and fundamental concept within many of the engineering disciplines.
This scale was designed to be used with a stack of US pennies (I recomend 6 pennies per scale). The holes on the beam are equally spaced from the centerline of the beam (2 pennies on the closer hole = 1 penny on the farther hole on the other side).
This shows the direct proportionality between the distance from center of rotation (which penny stack hole is used) and the force (weight of pennies) to teach a student the fundamentals of moments.
"The magnitude of the moment of a force acting about a point or axis is directly proportinoal to the distance of the force from the point or axis" - Shaeffer, R.E. Elementary Structures for Architects and Builders. pp. 33-39.
Moment = (Force) x (distance)
Print Cost = $1.12 (assuming $20/kg for filament)