A honeycomb core is created from a stack of metal sheets that are welded together using a serpentine weld path. Each sheet in the stack is welded to the sheet underneath. All the odd-numbered sheets, excluding the bottom sheet, are welded using a first serpentine welding pattern that includes a plurality of long welds and a plurality of short welds. All the even-numbered sheets are welded using a second serpentine welding pattern that includes a plurality of long welds and a plurality of short welds, such that the long welds of the second serpentine welding pattern are shifted from the long welds of the first serpentine welding pattern. When a sufficient number of sheets have been welded, the stack is trimmed to remove the short welds. The stack is expanded by pulling the sheets one from another to form the honeycomb core.