Early work on what would become SK8 focused on infrastructure rather than visual programming. Kleiman's first effort was a dynamic, prototype-based object system, MacFrames, a frame/object system with plug-ins for inference engines. Through preferences settings, MacFrames was used to emulate a large variety of object systems, including IntelliCorp's KEE. This research, in concert with users developing actual applications and prototypes at Apple, yielded the object model used in SK8. MacFrames was developed in Coral Lisp, which was acquired by Apple and became Macintosh Common Lisp.