From Gateway Software Productions:
CAD Closure allows you to generate geometric closures from the dimension text (not line properties) in your CAD drawing. Works seamlessly with AutoCAD but it is not required as CAD Closure contains its own built-in viewer. The closure graphic is developed in real-time as you select the text. CAD Closure will compute area and check curves to see if they are tangential. Curves are cross-checked between chord, radius, and length. Multiple report writers built in.