The piecewise reuse of soon-to-be-demolished cast-in-place reinforced concrete (RC) structures in new structural projects poses new design challenges. Unlike the disassembly of prefabricated structures guided by existing connections, deconstructing monolithic cast-in-place RC building structures requires original saw-cutting-scheme design, balancing technical constraints and geometrical requirements. While prior research mainly focused on flat rectangular element reuse, this study explores the cutting and reuse of saw-cut assemblies composed of both vertical and horizontal structural elements. Reusing monolithic assemblies made of mushroom column slabs, the rebuiLT pavilion is used as a case study to analyze the influence of the donor structure on the receiver project. The design and construction analysis of the rebuiLT pavilion provides insights into the challenges as well as the benefits of repurposing three-dimensional structural components.