Area overhead is reduced between adjacent blocks of a 3D vertical channel memory device. In various embodiments, vertically oriented pillars that intersect layers of string select lines and word lines are arranged at intersections of a regular grid that is rotated, in a “twisted” array of pillars. Sides of shapes of the 3D NAND array structure are undulating, and follow undulating lines in which the outer pillars are disposed. For example, any of the string select lines, word lines, ground select lines, and ground lines have sides with undulating shapes.