The mechanism suggested in the previous answer is a form offour-bar linkage. A bell crank is a slightly simpler form of basically the same thing. You could push on one side of a bell crank with the end of the motor shaft, and use a spring return for the other direction if it is difficult to attach to the shaft. (The shaft apparently rotates, but the Squiggle motors site doesn't say if it does or doesn't, and the pictures, videos, and technical drawing PDF files are not clear on this point.)