Avoid converting low-poly STLs. If the STL has visible triangles, the carved part will have faceted edges.
: If you own a licensed version, the ArtCAM Clipart Library contains over 500 free reliefs, including greenery, animals, and textures. free artcam relief files
You can import all of these into ArtCAM, or modern alternatives like Aspire, VCarve, or Fusion 360. Avoid converting low-poly STLs
GrabCAD focuses on mechanical parts, but the "Art" section contains free architectural and decorative reliefs. or modern alternatives like Aspire
: This tool allows you to "cut" a 3D shape out of an existing relief to save it as a standalone piece of clipart for future projects. Important Considerations When downloading free files from the web, check the licensing terms