In this study, we aim to widen the understanding of how students' collaborative knowledge practices are mediated multimodally in a school's makerspace learning environment. Taking a sociocultural stance, we analyzed students' knowledge practices while carrying out STEAM learning challenges in small groups in the FUSE Studio, an elementary school's makerspace. Our findings show how discourse, digital and other "hands on" materials, embodied actions, such as gestures and postures, and the physical space with its arrangements mediated the students' knowledge practices. Our analysis of these mediational means led us to identifying four types of multimodal knowledge practice, namely orienting, interpreting, concretizing, and expanding knowledge, which guided and facilitated the students' creation of shared epistemic objects, artifacts, and their collective learning. However, due to the multimodal nature of knowledge practices, carrying out learning challenges in a makerspace can be challenging for students. To enhance the educational potential of makerspaces in supporting students' knowledge creation and learning, further attention needs to be directed to the development of new pedagogical solutions, to better facilitate multimodal knowledge practices and their collective management.