A heat exchanger including a first reservoir, a second reservoir, and a heat tube including a body extending between the first reservoir and the second reservoir, where the heat tube defines a working region having a cross-sectional shape with an exterior wall enclosing a channel therein that is in fluid communication with the first reservoir and the second reservoir. The heat tube includes a curvilinear tube axis extending the axial length of the working region, and where the body of the working region includes the cross-sectional shape extruded along the curvilinear tube.