Revit is a powerful tool for architects and designers to create 3D models of buildings and structures. One key feature is the ability to create section views by using a cut plane in the 3D view. Here are the steps to put a cut plane in a Revit 3D view:

1. Open the desired 3D view in Revit. Go to the View tab on the ribbon and select 3D View. You can also use the keyboard shortcut VG to toggle the visibility/graphics of the view.

2. Once in the 3D view, go to the View tab on the ribbon and click on the Section Box tool. This will allow you to define the boundaries of the cut plane.

3. Click and drag the section box handles to adjust the size and position of the cut plane in the 3D view. You can also input specific dimensions in the properties palette to fine-tune the cut plane.

4. After setting the cut plane, the 3D view will now display a section view according to the placement of the section box. This can be useful for visualizing the interior spaces of a building or analyzing the relationships between different building elements.

5. To further customize the cut plane, you can use the Section Depth and Far Clipping properties in the properties palette to control the depth and visibility of the section view.

By using the cut plane tool in Revit, architects and designers can easily create dynamic section views in 3D models for better visualization and analysis. This feature allows for a more comprehensive understanding of the spatial relationships within a building, leading to more informed design decisions and improved communication with clients and stakeholders.