Trying to find a plastic item used as a substructure for wrapping posts. looking down on it the thing looks like a square with a hole cut in the middle. its made of plastic-I think-and is used on steel columns. they are hinged so that they open allowing one to put them on already installed columns. when several are in place on a post it allows the carpenter to align them. in other words when in place you have square surfaces to nail to and then install the trim to them. anyone know what these things are called and where to get them. they do exist. I saw an add for them several months ago, but of course cannot find it now. thanks.