We made them for a candle filled wedding - going up side (but not used) aisles in a BIG church. Used toilet bowl fixtures, I think for the top and bottom...
i don't exactly know what to call the mechanics. the are just bolted to a wood base w/ something that screwed in to the base and then in to the pvc pipe... we actually made the thing for a hoopa we did years ago and covered it all in tulle... the top you can just drop in a j4 mache.. and make your flowers in it