Create panel > Geometry button > Extended Primitives > Object Type rollout > ChamferBox button
Create menu > Extended Primitives > Chamfer Box
Use ChamferBox to create a box with beveled or rounded edges.
To create a standard chamfered box:
From the Create menu, choose Extended Primitives > Chamfer Box.
Drag the mouse to define the diagonal corners of the base of the chamfered box. (Press Ctrl to constrain the base to a square.)
Release the mouse button, and then move the mouse vertically to define the height of the box. Click to set the height
Move the mouse diagonally to define the width of the fillet, or chamfer (toward the upper left increases the width; toward the lower right decreases it).
Cube—Forces length, width, and height to be equal. You can change a cube's individual dimensions in the Parameters rollout.
Box—Creates a standard chamfered box primitive from one corner to the diagonally opposite corner, with individual settings for length, width, and height.

Length, Width, Height—Sets the corresponding dimensions of the chamfered box.
Fillet—Slices off the edges of the chamfered box. Higher values result in a more refined fillet on the edges of the chamfered box.
Length, Width, Height Segs—Sets the number of divisions along the corresponding axis.
Fillet Segs—Sets the number of segments in the filleted edges of the box. Adding fillet segments increases the edge roundness.
Smooth—Blends the display of the faces of the chamfered box, creating a smooth appearance in rendered views.
Generate Mapping Coords—Generates coordinates for applying mapped materials to the chamfered box. Default=on.
Real-World Map Size—Controls the scaling method used for texture mapped materials that are applied to the object. The scaling values are controlled by the Use Real-World Scale settings found in the applied material's Coordinates rollout. Default=off.