Patent attributes
This document discusses, among other things, a method of manufacture including a mold having at least one pin, and surrounding the pin with a hardenable material to form a first guide layer. The mold and pin are removed from the resulting first guide layer, to define a substantially untapered first instrument passage that corresponds to the geometry of the pin. Optionally, the first instrument passage includes at least five substantially untapered channels including a central channel. The first instrument passage is aligned with a substantially untapered second instrument passage of a stacked second guide layer. In a further example, the first and second guide layers are coupled to a guide coupler that cooperatively aligns the first and second instrument passages. The guide layers can be used with a trajectory guide for image guided surgery.