Light Weight Ribbed Mirrors Pause for a moment to remember George Willis Ritchey, the pioneer of ribbed mirror technology. His method of gluing glass structures together is now obsoleted by thermal fusion bonding techniques of the great Canadian mirror making teacher, Ric Rokosz. Since the palomar 200, most great telescopes use light weight ribbed mirrors. Telescope makers can learn a lot from aircraft designers.
Less glass is used, the cost is reduced.
Commonly available thin salvage glass can be used, the cost is reduced. The thermal mass is less, so the mirror cools to operating temperature quickly. Unless the mirror is VERY large, commonly available glass can be used. You will never be obstructed by large industrial companies who are difficult or impossible to deal with. If you use beam theory to estimate the flexure, you will have a conservative design.