While reports of teachers' use of curriculum materials are common, that of teachers as designers of their own materials are far less so. We argue that these (rare) instructional materials, defined as materials that are classroom-ready and that carry the teachers' actual instructional goals, are 'objects' that are suitable as records of teachers' planning and learning when developed alongside professional development. We provide supporting evidence of this claim and unpack the complexities of interacting instructional goals through a case study of a teacher who (re-)designed her own instructional materials as she participated in professional development. From the findings of the case, we reflect on the educational and methodological implications of pursuing this research approach.