Hi, I wouldn't make a whole secondary cage. If you mount at the top of each 4 spider vanes a screw connected to the cage you can do the same as you suggest but with less weight. Anyway good idea ! Johan Vanbeselaere ACG vzw Belgium http://www.digilife.be/club/johan.vanbeselaere/atm/optics/mirrorcell/mirrorcell.htm