Why do I only get the choice of a Silhouette boundary with a V3M model?

The V3M file format from Vector Art 3D is a unique format which includes a special boundary to ensure the toolpaths stay on the 3D surface.

If you have purchased a V3M model but find your current project requires more toolpath flexibility, you can download the same exact model in STL format from the Vector Art 3D website at no additional cost.