ACIS (SAT)<=>3D DXF<=>GERBER<=>GDSII<=>IE3D is built in on the layout editor (MGRID) in IE3D 10.2. A user needs the ADIX license to enable the feature (except GDSII<=>IE3D).
In case your's IE3D is below 10.x you can use LinkCAD hxxp://www.linkcad.com/ , but this one allow import /export of planar structures only as are :
AutoCAD® DXF™, Gerber RS-274X, GDS-II™, CIF, PostScript®, IE3D . So this case the better way is to make export from SAT to any another format first and make import to IE3D after that.
IE3D10.21 time-limited trial siut you can obtain at the zeland web site after registration.
regards.