A high performance objective having very small central obscuration, an external pupil for apertureing and Fourier filtering, loose manufacturing tolerances, large numerical aperture, long working distance, and a large field of view is presented. An example method comprises providing one or more shaping elements, softening the material, and urging the one or more shaping elements against the material so as to form one or more grooves in the material. An elongated guide portion runs parallel to and is spaced from the locking tang between the pipe segment and the locking tang. The circular sheets are connected sealing to the peripheries of the notches of the petal-shaped sheets to form the sphere like body once inflated.