Each AutoCAD drawing contains at least one layout space. A layout space differs fundamentally from the (singular) model space, in that every layout space has edges corresponding to a specific paper size.
Model space and layout space.
Each AutoCAD drawing contains only one model space; however, a model space is practically infinite in extent (no edges). Drawings are usually created in model space, and layout space (also called paper space) is used to format views of those drawings on paper.
When a layout space is initially activated (the first time the corresponding Layout tab is clicked), AutoCAD displays a default page size with a single viewport (see below). Type PAGESETUP to bring up the Page Setup dialog box, prompting you to define a printer and paper size. Each layout space in a drawing may be formatted for a unique printer and/or a unique paper size.
When a layout space is initially activated, AutoCAD automatically creates a viewport. So-called paper space viewports are analogous to windows or holes in a piece of paper through which a drawing can be viewed at a particular scale. Using viewports, multiple views of a single drawing, or of multiple drawings, may be formatted on a single layout (i. e. a piece of paper). Each viewport may be configured with its own settings for scale and layer visibility.
Basic viewport operations.
To delete an existing viewport: type PS [enter], then type E [enter], select the viewport (click on its edge), [enter].
To make a new viewport: type PS [enter], then type MV [enter], then click on two points (a corner and an opposite corner) to define a rectangle.
To resize an existing viewport: type PS [enter], then click on the existing viewport, and drag its corners to new locations.
To copy an existing viewport: type PS [enter], then type COPY [enter], click on the existing viewport, [enter], and indicate base and displacement points.
To move an existing viewport: type PS [enter], then type MOVE [enter], click on the existing viewport, [enter], and indicate base and displacement points.
To make the frame around a viewport disappear: type PS [enter], then click on the boundary of the viewport, and use the layer pulldown palette to assign the viewport to a new layer. Turn this layer off, or freeze the layer.
Viewports and scale.
By definition, when a model space drawing is viewed through a paper space viewport, the drawing is seen at scale. The ratio between the actual size of the drawing and its printed size is called the scale factor.
Changing viewport scale. To change the apparent size (i. e. the scale) of a drawing within a viewport: type PS [enter], then click on the edge of the viewport, then click on “Standard Scale” and select a scale from the list.
OR… Type MS [enter], click inside the viewport, type Z [enter] (for ZOOM), and then type 1/nXP (where n equals the desired scale factor, such as 1/96 for 1/8” = 1’-0”).