mtInset generates inner extrudes from the faces of your base geometry.

Cube as a child of mtInset, with an Inset Mode setting of Face Percentage and an Amount value of 50%.

Object tab

Selection Map

You can use a vertex map or selection tags to define where insets are generated.

Drag the tag from the Object Manager into the Selection Map link field.

The Plane on the left has a polygon selection tag, which is displayed in the viewport. An identical lane is on the right, as a child of a mtInset, driving where insets are generated.

The Plane on the left has a vertex map, which is displayed in the viewport. An identical Plane is on the right, as a child of a mtInset. The vertex weights are driving the generation of insets.

Texture Source

You can use shaders, images and even animated video sequences to control where insets are generated.

There are two options: Shader and Texture Tag.

Both use color value to define which areas are affected.

Shader mode

Shader

Use the Shader drop-down to select an image, sequence or shader.