Adobe Repoussé is a tool for turning 2D paths into 3D meshes. The term Repoussé is derived from the art creating a shaped metal piece by hammering from the reverse side. You can use the Repoussé feature to take a layer and add dimension.
Once in the Repoussé dialog box, you can apply a 3D preset to your object, or customize your own using the Materials, Extrude, Bevel, Inflate, Scent and Internal Constraints settings.
In this tutorial: