Best for technical CNC parts rather than artistic reliefs.
If you are a student or a hobbyist (making under a certain amount of revenue), Fusion 360 is free. It is more of a traditional CAD/CAM package but is extremely powerful for 3D machining. artcam 91 pro free
Since ArtCAM is no longer supported, most CNC hobbyists and professionals have moved to modern alternatives: Best for technical CNC parts rather than artistic reliefs
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. artcam 91 pro free