Select Diffuse Map and select Checker as the map type.
Click the down arrow button for the Click for Checker Settings
for additional property settings for the map.
For Color 1, select Speckle as the map type. For Color 2,
select Wood as the map type.
After changes are made, at the top of the properties settings
window next to the Nested
Map Navigation name display and down arrow
button, click the icon Up One Level to Parent Map to return to the
top level map. It is an icon with three circles and an up
arrow.
To display a larger view of the material swatch, click the
Preview Map Channel Procedural Results button. It is the last
button in the Diffuse Map area with a cube and magnifying glass.
You will see how the nested maps patterned in the checkers.
Click the drop down arrow in the Nested Map Navigation panel.
You will see the nested list of the material. The list will show
the Material name, Diffuse Map: Checker, Color 1: Speckle, and
Color 2: Wood.
The Map Synchronize toggle button can enable any change of
Tiling & Scaling or Offset & Preview at the nested level to
affect all map levels. If control of the Tiling & Scaling or
Offset & Preview needs to be at the nested level, then disable
the Map Synchronization toggle button.
NoteEach
procedural map type has different property settings available.
Refer to the specific property settings described under the
Map
Property Settings topic found under the MATERIALS
command.
Toolbar: Render 
