This invention relates generally to: (1) methods of forming enhanced-surface walls (20) for use in apparatae (e.g., heat transfer devices, fluid mixing devices, etc.) for performing a process, (2) to enhanced-surface walls per se, and (3) to various apparatae incorporating such enhanced-surface walls.The method improved method broadly comprises the steps of: providing a length of material (21) having opposite initial surfaces (22a, 22b), said material having a longitudinal centerline (x-x) positioned substantially midway between said initial surfaces, said material having an initial transverse dimension measured from said centerline to a point on either of said initial surfaces located farthest away from said centerline, each of said initial surfaces having a initial surface density, said surface density being defined as the number of characters on an surface per unit of projected surface area; impressing secondary patterns (23a, 23b) having secondary pattern surface densities onto each of said initial surfaces to distort said material and to increase the surface densities on each of said surfaces and to increase the trans-verse dimension of said material from said centerline to the farthest point of such distorted material; and impressing primary patterns (25a, 25b) having primary pattern surface densities onto each of such distorted surfaces to further distort said material and to further increase the surface densities on each of said surfaces; thereby to provide an enhanced-surface wall for use in an apparatus for performing a process.