3Ds Max - Face Extrude
Face Extrude
Face Extrude modifier adds depth to a shape object and makes it a parametric object, and the Face extrude modifier faces along their normal, creating new faces along the sides of the extrusion that connect the extruded faces to their objects.
Step1: Create a box and convert the box to editable poly.
Step2: Select polygon option of selection and select some faces of boxes.
Step3: After that click on modify tab and select face extrude tool.
Step4: Specify extrude height.