MeshToSpline is a modifier that takes a mesh & turns it into splines so it can be used with Surface Tools. Right now it is in its very early beta stages and only supports regular meshes and capped regular meshes. A regular
mesh is mesh that odered vertices with constant U and V counts examples of regular meshes are grids, torus, cylinders or circles with the capping vert removed. Supported primitives are sphere, cylinder, torus, tubes, grids, and
cones. Lofts are not yet supported but will be shortly.