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Lesley and I created a lever set (with 100% reused materials) to experiment with and demonstrate first, second and third-class levers. Our working model was made from masonite arms, wooden dowels for pivots and linkage points, some gears for spacers and a couple metal parts as simple counterweights.
To calculate the forces involved we use the formula Torque = Force × Distance to fulcrum × sin ϑ. Since sin ϑ is 1 at 90 °, this reduces to Torque = Force x Distance. According to my calculations, our experimental system produces a 55% reduction in force, with a proportional increase in travel distance, as demonstrated in the video.
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