Transformative STEM learning spaces have grown rapidly in schools, libraries, and museums as “Learning Labs” or “Makerspaces.” This paper introduces an elementary and middle school project-based learning-integrated curricular approach and Makers’ Guild professional development program that introduces participants to STEM career pathways using challenge cards. Makerspaces provide opportunities to assist organizations in efforts to improve teacher attitudes and confidence levels toward STEM and instructional technology. This study investigated a Makerspace professional development program, the Makers’ Guild, provided to teachers within North Texas over the course of a semester and was funded through a NASA Makerspace outreach grant. The research employed a constructionist approach delivered via instructional methods incorporating 2D and 3D technologies during STEM instructional activities within a creative space. Participants reported a statistically significant increases in self-reported competence in technology integration, confidence levels toward integrating World Wide Web, emerging technologies for student learning, teacher professional development, and attitudes toward math, technology, science, and STEM careers.