UPDATE: This is obsolete. There are better Scotch Yokes available on Thingiverse, including my own at https://www.thingiverse.com/thing:1017672

This is a rough and uncompleted design for a Scotch Yoke. As shown, it will not work - there's nothing for the crank to turn on. I hope to add some features over the next few days so that this can serve as a basic demonstration of the linkage.