<p>Aluminum foam sandwich structures, featuring excellent lightweight properties, play a crucial role in energy conservation and carbon emission reduction. However, the direct fabrication of large-scale structures via a single expandable precursor is limited by equipment pressure and mold dimensions, rendering the multi-precursor method widely applicable. This study investigates the foam growth and interfacial bonding behaviors of two and three AlSi8Mg4-based precursors under different constraint conditions. Results indicate that in hollow cavities, precursors can form an integrated structure with metallurgical bonding, whereas unconstrained free foaming leads to uneven pore distribution and high collapse susceptibility. Under the constraint of a closed-type cavity, heat conduction and phase change proceed from the middle toward both ends. Due to the constraints of the closed-type cavity, both dual-precursor and triple-precursor materials can achieve good bonding and form a unified whole, with the pore structure showing a trend toward homogenization, allowing the production of high-quality aluminum foam. Mechanical performance indicates that the fracture mode and ultimate load of the dual- and triple-precursor samples are consistent with those of the single-precursor samples.</p>