The SKP file is the main file type used by SketchUp that allows conceptual designs to be created, viewed, and shared quickly and easily. When you create a new document and save it in SketchUp the SKP file is created to store the document and its contents. SKP files can also be used to store SketchUp components, which are objects, such as a door or window, that you can reuse to save time. Components may be made by you or another user and can be imported into an SKP document to be inserted into your model. Download free skp 3d models.