Convert DXF to FLT

Your best option for working and possible also export of MultiGen formats (.flt) would be to use the open source Blender software. With this program you should be able not only to edit, but also export .flt files to or from several other 3D formats or 2D CAD format, including common DXF format, which is what dxf to fit conversion is. But of course, there may be more programs capable of this conversion.