Perkin-Elmer fabricated two 9.5 in. (24.1 cm) diameter beryllium mirror blanks using an advanced powder metallurgy process to produce mono-lithic, lightweight (2.16 lb = 0.98 kg) structures with honeycomb interiors. The new beryllium material exhibits improved isotropy as measured by x-ray diffrac-tion techniques. The mechanical properties meet or exceed the published values for commercially available vacuum hot pressed beryllium block. In addition, the material is readily polished to good figure and surface quality and has demonstrated potential for lower scatter than standard material. The monolithic sandwich construction demonstrated in the program is exceptionally stiff, permitting large lightweight mirrors to be constructed. A scaled-up 36 in. (91.4 cm) diameter mirror would weigh only 31 lb (14.1 kg) using the technology demonstrated in the project. It is estimated that with minor modification in the process this weight could be halved.