This paper proposes a new ideation technique for how to ideate using sketching and a generative design system based prototype tool. The technique is aimed to support ideation through the exploration of design shape deviations. The tool generates 3D model artifacts with variations in their shapes. The overall shape and deviations are based on a design concept specified by the user of the tool. These design artifacts are then used as a means to rediscover one's own design concepts through the theory of estrangement. A study was conducted where university-level design students tested the technique in a scenario where they were tasked with ideating product design solutions. The performed study (along with post-study interviews) revealed promising results where participants of the study described their experiences as fun and interesting. The design outcomes of the study display how participants worked and iterated on their conceptual artifacts. They explored different and new angles of the design space relative to their concepts by using the generated design artifacts. This may suggest that this technique, using computer-generated concept deviations can be a successful way of supporting ideation by expanding on one's design concepts, rediscovering concepts, moving beyond obvious solutions and iterating design concepts.