Randy - I have a short post on the concrete railing previously and also on the early pages on the TPRR.
Basically its foam insulation routed to produce an I-beam shape and then used a 1/4 inch up-cutting router bit on my drill press for the columns. This bit has sharp sides which will cut out the columns when the work piece is slid up to make the column. Scale wise they are a touch too big but work visually. All coated with grout mix then color washed. I set up a kind of jig and ran a bunch off in a few minutes. Getting the speed right is the only real trick - too slow and the foam tends to tear out. Too fast and the router bit wants to reduce the amount of flesh on your fingers. I would not recommend a high speed router to do this, although if you had a router table and speed control that would work for making the I-beam shape. I suppose you could make this a glued up assembly out of wood. But since I had curves, I though the foam would bend pretty well and it did.
Thanks for the referral to your other post. It has given me an idea.