Jeremy’s video is accurate. There is an easier way once you’ve downloaded and installed OpenSCAD. At the top of the app, click View, then unclick “Hide Customizer”. That will display the different parameters and their choices that Jeremy explained in his video. \ Under the Parameters twistie in that window, fill in the parameters that are needed, then in the top drop down of Customizer, choose each entry and perform the Preview, Render, and Export as STL.