A support structure (60, 110, 130, 160) for a three-sided scallop (48) in an edge of a stent graft (10) includes two substantially longitudinal perimeter support sections (66, 124, 144, 172) and an undulating lateral side base (62, 112, 132, 162) extending between the two support sections. The undulations extend below the edge of the lateral side of the scallop and overlap the graft material away from the edge of the lateral side.
