Patent ID: 7303861

Claim:
A method for making a forming structure having columnar protrusions extending therefrom, the method comprising the steps of: a) providing a forming unit; b) providing a backing film; c) providing a foraminous element; d) juxtaposing the foraminous element and the backing film with respect to the forming unit so that the backing film is interposed between the foraminous clement and the forming unit; e) providing a liquid photosensitive resin; f) applying a coating of the liquid photosensitive resin to the foraminous element; g) juxtaposing in contacting relationship with the coating of photosensitive resin a first completely transparent mask; h) controlling a first thickness between the backing film and the first mask of the coating to a preselected value; i) exposing the liquid photosensitive resin to light having an activating wavelength through the first mask thereby inducing partial curing of the photosensitive resin to form a monolithic slab of partially-cured photosensitive resin; j) removing the first mask; k) repeating steps (a)-(j) one time with a different, second mask replacing the first mask in steps (g)-(h) and a second thickness in step (h), the second thickness being defined between the backing film and the second mask and being greater than the first thickness, and, in step (i) inducing partial curing of a plurality of protrusions on the monolithic slab such that they are joined to and integral with the monolithic slab, and removing the second mask in step (j); l) immersing the foraminous element and partially cured resin thereon in an oxygen-free environment; m) exposing the foraminous element and partially cured resin thereon to light having an activating wavelength to fully cure the partially cured resin, resulting in the forming structure having columnar protrusions extending therefrom.