A concrete pillar or a concrete footing. On this old house they use a form that they sell at most home improvement stores like home depot or lowe's or 84 lumber.then you have to know how to suspend some rebar in the form to make the pillar stronger. Now if your talking about a ornamental pillar that would depend on what your wanting it to look like. On one show I watched they used a styrofoam form to make their posts/pillars. But I have no idea where they sell those at.I suppose you could use a piece of pvc pipe split in half length ways to make a form to pour the cocncrete in then you can take the form loose from the concrete after it dries. You would have to make a way to clamp the pipe halves together in order to be able to make a hinge in order to take the form loose after the pillar dries enough to remove.this is all I can think of besides looking on the this old house web site.
