I downloaded the trail version of obj mesh to solid. http://www.resurf3d.com/Objmesh2solid.htm It does what it purports. It does not like triangles very much. the best way to use it is to make your mesh all quads otherwise if you have to many triangles it hangs. It smooths things out nicely but the problem with it is taking a large file and converting it means you have a large solid file so not an elegant solution.

I have also tried stl to step. http://www.solveering.com/products/products_stl2step.html I didn't think it was that useful but maybe some one else might.

Val