As robots become more pervasive, operators will develop richer relationships with them. In a 2 (robot form: humanoid vs. car) x 2 (assembler: self vs. other) between-participants experiment (N=56), participants assembled either a humanoid or car robot. Participants then used, in the context of a game, either the robot they built or a different robot. Participants showed greater extension of their self-concept into the car robot and preferred the personality of the car robot over the humanoid robot. People showed greater self extension into a robot and preferred the personality of the robot they assembled over a robot they believed to be assembled by another. Implications for the theory and design of robots and human-robot interaction are discussed.