Create panel > Geometry button > Extended Primitives > Object Type rollout > Gengon button
Create menu > Extended Primitives > Gengon
Use Gengon to create an extruded, regular-sided polygon with optionally filleted side edges.
To create a gengon:
Set the Sides spinner to specify the number of side wedges in the gengon.
Release the mouse button, then move the mouse vertically to define the height of the gengon. Click to set the height.
Move the mouse diagonally to specify the size of the chamfer along the side angles (toward the upper left to increase the size; toward the lower right to decrease it).
Tip: In the Parameters rollout, increase the Fillet Segs spinner to round the chamfered corners into fillets.

Sides—Sets the number of sides around the gengon. Higher numbers shade and render as true circles with Smooth on. Lower numbers create regular polygonal objects with Smooth off.
Radius—Sets the radius of the gengon.
Fillet—Sets the width of the chamfered corners.
Height—Sets the dimension along the central axis. Negative values create the gengon below the construction plane.
Side Segs—Sets the number of divisions around the gengon.
Height Segs—Sets the number of divisions along the gengon's major axis.
Fillet Segs—Sets the number of divisions for the edge filleting. Increasing this setting will produce round, filleted corners instead of chamfers.
Smooth—Blends the faces of the gengon, creating a smooth appearance in rendered views.
Generate Mapping Coords—Sets up the required coordinates for applying mapped materials to the gengon. 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.