Limits on sketch, image, body, axes and plane files and how they are stored in items manager

  1. How to establish sketches so they are not including or omitting unwanted lines, shapes and curves?

2)I find myself creating custom angles and work flows on what are customarily; rudimentary, basic, calculations, my model seems like it is becoming more difficult to deal with;….then I back way out of the design and I see deeep field of space junk and forgotten shapes, objects and lines. So if the work space is 1kilometer squared, is there a way to set up a perimeter of 5 or ten meters squared and be able to delete everything on he outside of that perimeter? ,