The Archive still has the IFC 1.1 distribution, as well as Constructor:

http://web.archive.org/web/19970615200826/http://developer.netscape.com/library/ifc/

and a screenshot:

http://web.archive.org/web/19970615123220/developer.netscape.com/library/ifc/constructor/screens.html

If you download the code and copy the 3 folders under ifc11/netscape/ from the IFC distribution into constructor10b3/Constructor.applet/netscape in the Constructor distribution, then open index.html with Safari, Constructor will actually run. It also works with the Mac OS X Applet Launcher.