The image above shows the full interface of qcad in dark mode, it is possible to change it to light mode if you wish, but I will leave it in dark mode through-out this tutorial. Notice the toolbar on the left side for drawing lines and circles etc and the layer list on the right side. Layers are very useful because you can make each line a different colour if you wish so that is easy to distinguish projection lines from intersection lines for example. In the next paragraph I will show you how I developed an offset square-to-round transition piece in QCad, coming soon....