If they are not structural, you could use styrofoam columns.
We are a national manufacturer of EPS (styrofoam) products. We currently catalog over 300 shapes (including columns and balustrades) with 10 to 15 shapes available, in small or large quantities, for immediate delivery.
Please visit us online at quantuviseps.com. An online catalog is available on the brochure tab. If you are unable to download the brochure, please contact our sales department at firstname.lastname@example.org and we will either email one to your or send you a hard copy (your choice) or you can contact me directly at 619-654-7076.
VP Sales and Marketing