The parts of this device include a sliding bar, a yoke on the bar (in the middle) with a slot cut out, and a smaller bar connected to the yoke and affixed by a pin through the yoke slot to the sliding bar. As the bar slides back and forth, or reciprocates, the smaller bar is forced to slide up and down in the yoke slot, creating a rotational movement. The converse of this motion relationship is also true; as the pin initiates a rotational movement, the slider correspondingly generates a reciprocal or back and forth movement. 

The model

The model we need to build is a  prototype for the purpose of 
demonstrating the operation of the Scotch yoke mechanism 
with regards to its conversion of angular velocity to linear 
velocity. The specifications of the components that are used 
in its construction are as follows: 
The Base Frame: the frame has to be designed by Solidworks according to the example shown on the "video page" and then printend by a 3D printer in PLA. The dimensions of the frame are depending on the diameter of the pistons and the length of the linear slider, so it has to be calculated.
The Scotch yoke 
mechanism: the Scotch yoke mechanism consists of 
following singular members conjoined and assembled in the 
appropriate manner: the slider, yoke or slot, Crank pin, 
and crank. The assembly has to be designed and printed. The linear slider has to be affixed to the 
yoke member in a rigid manner or built as a one piece. The crank has a recess into which the motor shaft of the electric motor entered and rigidly fitted.

It also consists of two cylinders and pistons connected to flexible hoses.