How do I convert dxf 3D curves (thousands) into either a surface or a solid?

I'm working on a part that was modeled in Blender. I have several files of varied resolutions exported as 3DF dxf files (>300K to 13K imported curves). I'm curious how best to turn this geometry into surfaces or a solid. The Blender export totally screws up the scale of the part- I think  but would appreciate ideas on how best to re-scale the geometry. Thanks

SolidworksSurfacing