We follow in the “constructionist” tradition of mathematician and educator Seymour Papert and his students and colleagues at MIT. In developing the Logo programming language for children Papert argued that programs children write function as mathematical ‘objects to think with’ and that their concreteness affords a powerful kind of learning (Papert, 1980). Later work of Papert’s former students and colleagues (. Mitchel Resnick’s group at MIT) has explored and extended this idea, moving beyond the inner world of software into the hybrid world of physically embodied computation (Resnick et al., 1998). Michael Eisenberg and his craft technology group, our collaborators.