On November 9-11, 1998,85 participants, representing 17 countries, gathered in Aubum Hills, Michigan, at the Chrysler Tech Center, to attend a workshop "SSM'98" (or Sculptured Surface Machining '98) organized by IFIP Working Group 5.3. This was the first major workshop on sculptured surface machining since the CAM-I sponsored conference "Machining Impossible Surfaces" held in 1981. The purpose of the SSM'98 workshop, entitled "Machining Impossible Shapes", was to promote a cross-fertilization of ideas among three communities: industrial users, CAM software developers and academic researchers. There were 17 participants who were "industrial users", 15 represented CAM software developers, 4 were from the machine tool industry, with the remainder being academic researchers. The format of the meeting included 40 presentations in 9 sessions, 4 keynote speeches and a sufficient amount of time for informal discussion amongst the participants. One of the most valuable aspects of the workshop was the opportunity for participants to meet informally and to discuss their mutual interests. This led to two "participant organized" sessions on five axis machining and on machine tool controllers.