Abstract: A boom for an excavator or the like is constructed to have a generally L-shape when viewed in side elevation and have a circular cross section tapering downward from a maximum diameter at the apex of the boom to each end. The boom is made up of a central body portion consisting of a cast-form elbow and a pair of tapered tubular members formed of rolled plate welded along a longitudinal seam extending from the elbow outward to the outer ends of the boom. A pair of cast-formed connecting members are then welded to the end of the boom. The method of fabrication includes the cast-forming of the elbow and the respective end connecting means and forming the tapered body members by rolling and connecting the entire assembly by welding.