Too bad you do not have a laptop with Microsoft Office because "Visio®" is a very easy program to use. I used professionally for conceptual chemical engineering designs. I understand SmartDraw reportedly offers a powerful and easy-to-use solution if you want a Visio® alternative on a Mac. SmartDraw reportedly offers more templates, better tools, industry-leading automation. Also take a look at the link below entitled "Best Free Drawing Software for Mac" for potential drawing apps for Mac..............does anyone know of a good schematic drawing app for a Mac computer?