“This is a machine which draws a torus. It is based on a ruler, two modified servo motors and some 3D printed parts. One of the motors has a 3D printed wheel attached with offset mounting holes. The marker slider is attached to this wheel with a metal linkage. As the 3D printed wheel turns, the marker slider moves back and forth linearly across the ruler. At the same time the other servo drives the entire machine in circles around a center pivot using a skate wheel. These two simultaneous movements ultimately move the marker and draw the torus design. This was created to help support a 7th grade curriculum, but surely can be used at other grade levels. See the attached lesson plan for how you might use it in the classroom to explore area and circumference.If you are looking for a machine for younger students that demonstrates simpler mathematical and engineering principles, check out the Circle Drawing Machine.”