A relief file (.rlf) contains surface topology data. It allows a CNC programmer to take a complex object—say, a decorative floral scroll or a dragon’s head—and instantly apply it to a surface, rather than modeling it from scratch.
Alternatively, download the standalone SetupAutodeskArtCAMReliefClipartLibrary2018.exe (approx. 900 MB). Select Relief > Clipart Library from the top menu. Artcam Relief Clipart Library Download