According to one embodiment of the invention, a method of making a collimator for a detector array of an x-ray technique-based nonintrusive inspection apparatus is provided. The method includes injecting a die with a material, the die being shaped and dimensioned to form a collimator including a body defining a support structure and a plurality of septa secured to the support structure; allowing the material to set within the die to form the body; and removing the body from the die.