LOW-COST CAD Drafting software costing from $80 to $800 can give you features and power once the domain of mainframe computers. MacDraft offers easy, attractive sketching, but without precision. Here is a kitchen floor plan from MacDraft printed on the Apple Imagewriter. BY BILL SMITH Just as word processors have changed the way many people write, computer-aided design and drafting systems will probably change the way you draw. Switching from traditional drawing methods to computer-aided design, however, does have its complications. Besides the cost of the hardware and software, you can expect to spend quite a bit of time setting up the equipment and learning how to operate even basic CAD features. Mistakes and