Nesting
In some 2D designs you can save material and cost by placing one part inside another. Although the CAD software does not currently allow that type of nesting you can circumvent this as in the following example:
By adding the gap in the ring, the outer part no longer fully encloses the inner part. As a result the CAD software allows the design. The Comments To Machinist (red lines and text) clarifies that you really want the ring closed.
