Abstract: A sizing die for sizing a plurality of micro-extruded tubes has a side fence, a clamping fence in substantial parallel relation with and movable with respect to the side fence, a base fence adjacent to and perpendicular to ends of the side fence and the clamping fence, and a movable die platen for applying pressure to the top of the stack of tubes. The side and base fences preferably are fixed. The tubes to be sized are stacked on their sides against the side fence with their internal webs aligned throughout. The clamping fence and die platen are moved to be in mating engagement with the stack. Pressure is applied through the die platen against the top of the stack to compress the tubes to a desired thickness.