Add a plane mesh (Shift+A > Mesh > Plane). Subdivide it heavily (at least 500x500 segments).
Download BlenderCAM. Install it (Edit > Preferences > Add-ons > Install). Select your relief mesh, choose an operation (e.g., 3D Surface Finish), set your tool diameter, and generate G-code. artcam 91 pro free
Blender is a professional-grade 3D modeling suite. While its interface has a learning curve, it’s vastly more powerful than ArtCAM for organic shapes. Install the free BlenderCAM add-on, and you can generate 3-axis toolpaths directly from your sculpted models. Add a plane mesh (Shift+A > Mesh > Plane)