Abstract: An exchanger and method for manufacturing the same are disclosed. In one embodiment, the exchanger crimps a hollow fiber bundle along a length of a cylindrical case in at least two radial positions. At least one crimp is between an inlet port and an outlet port of a blood conduit. Preferably, the cylindrical case has two portions with different radii so that when the two portions are mated to enclose the hollow fiber bundle, crimping is achieved. In this way, shunting of blood is avoided by being forced to pass a crimped position between the inlet and outlet ports to more evenly distribute the blood among the fibers of the bundle. In another embodiment, a method for making an exchanger includes filling a chamber, integral to the exchanger, with uncured potting material. The exchanger is spun to distribute the uncured potting material about open ends of an encasement. After curing, a portion of the potting material and the hollow fiber bundle are trimmed away.