I don't believe it. First of all, a cloth will always form a "developable surface" i.e. gaussian curvature=0. However, a "dome" has positive curvature, and various hyperbolicish "minimal surfaces" (minimal surface ==> rigid, which is a useful property for some constructions) have negative curvature. So the technique is mathematically wrong. It also physically sounds like bull, because I have trouble seeing how you are going to make a dome larger than a house, then "invert it." In the case of the Duomo in Florence, by the way, it weighs about 40,000 tons. Want to just "invert" that? Meanwhile, the balloon+spray on technique has been used, and continues to be used, to make domes larger than houses (some of them, in fact, are houses, storage facilities, churches, etc). And you can design the shape of the balloon to make your domes have pretty controllable and somewhat intricate shapes, not just a plain spheroid. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)