About DIY 3D Drawing
Creating 3D images for a beginner it may seem difficult, where to start, but if you are a beginner already proficient in 2D it does not matter, now living understanding of 3D images, the 3D image is a 2D image in extruded (made no elevation), the altitude will be apparent if "WCS" was changed to be "UCS", for a position in the "WCS" its 3D images will not be visible, because the position of "WCS" the same as you see from the top. Imagine you see a matchbox when viewed from above, it is visible only a rectangular shape alone, as if the match is only in the form of a rectangular course, now your position in the fox that had been viewed from above now look on the door side, it would appear that these matches turned out to have a height.
You need to know the function extrude will be in use when the object is a entity, eg circle, ellipse and rectang, if you create a grid by using the "LINE", it has not become a single entity, you must perform the function of "PEDIT" or "REGION" sometimes while doing pedit difficult or often fail because there is a gap that is not visible to our eyes, it is often experienced by the drafter beginners.