How to make a balloon column (By the way, there was a site that talked about the Italian convention, with some insight of the behind the scenes construction of the temple, and they described slightly how Chris constructed the columns (For some reason the site doesn't come up any more). He used 4 inch PVC drainpipe (attached securely to bases I assume, they didn't specifically say), covered them in two-sided carpet tape, then affixed the inflated 260's to the tape.
Column Pedestals Probably less expensive than "plaster/resin" traditional columns at Hobby Lobby, and you can custom-size. For church, I'd prefer paint, without the "aged" look, in a color that blends with altar wood. These were made from 8ft- 4x4 wood cut into different lengths with a circular saw: Wooden Post base trim (found with deck railings and posts). Square piece of wood for the top of the pedestals. Church would require much larger sizes: 4 ft, 3 ft, 2ft?