The invention includes a method of joining edges of adjacent honeycomb core panel sections. In one embodiment, the method includes forming a first edge along a first cellular core panel section. The first edge includes a first plurality of edge cell walls along the first edge. The method further includes forming a second edge along a second cellular core panel section, wherein the second edge includes a second plurality of edge cell walls along the second edge. The first edge is positioned proximate to the second edge. At least a portion of at least one of the first plurality of edge cell walls is mechanically interlocked with at least a portion of at least one of the second plurality of edge cell walls to form a joint therebetween. The invention also includes a composite structure at least partially produced by such a method.