A motionless mixer for use in mixing flow streams in a conduit and a low-cost method of manufacturing the motionless mixer, which method comprises: cutting, such as by stamping, an elongated strip from a flat sheet, which strip comprises a plurality of connected, semielliptical blade elements; bending the strip at the connecting point between the blade elements, to form a plurality of blades at an angle of about 30.degree.-45.degree. to each other in the strip; providing first and second strips and aligning the first and second strips in a generally parallel arrangement; twisting the said first and second strips into a cooperative relationship, wherein each pair of blade elements is disposed at an angle of about 90.degree. with respect to each other pair of blade elements; securing the blade elements together such as by welding at the crossover point of the pair of blade elements, to provide a motionless mixer; and inserting the motionless mixer in a conduit.