A method of fabricating a mixer for a gas turbine engine is provided. The method includes forming a forward end and an aft end of the mixer, and forming an annularly undulating contour that defines a plurality of core immersion lobes and a plurality of bypass immersion lobes between the forward end and the aft end. The plurality of bypass immersion lobes includes a first bypass immersion lobe and a second bypass immersion lobe. The first bypass immersion lobe has a first crown contour line extending from the forward end to the aft end of the mixer, and the second bypass immersion lobe has a second crown contour line extending from the forward end to the aft end of the mixer. The first crown contour line is different than the second crown contour line.