A photon collimator, suitable for use in medical imaging equipment, is constructed from a block of photon-attenuating material, such as solid tungsten or molybdenum alloy that defines a plurality of integrally formed septa slats. Each slat has an elongated length dimension greater than thickness and depth dimensions, and is oriented in an opposed pattern array that is laterally spaced relative to its respective thickness dimension. An aperture channel is defined between each pair of opposed slats. Rows of integrally formed slats in one block or separately affixed blocks may be stacked on each other at skewed angles to form two-dimensional grids of apertures having polygonal cross sections. The slats may be formed by electric discharge or laser thermal ablation machining, such as by a sequential passing of an EDM wire cutting head along the pattern array, repeating sequential cutting of respective channel depth and width.