Choose the size of cardboard tube form you need for your pillars. They range from 6 to 18 inches with larger sizes available for special order. Mark the tube at the height you need, raise your table saw blade up as high as it will go and set the fence to cut off what's needed. Start the saw and spin the tube through the blade to cut all the way around evenly.
Trace the inside of the tube onto a piece of 3/4-inch plywood. Cut two circles, one for the top and one for the bottom at this size using a band saw. Use a compass to draw a circle 1 ½ inches wider than that and cut two for each column. Center a smaller circle on top of a larger circle and glue and nail them together. Do this twice for each pillar.
Fit the ends into the ends of your concrete form, the smaller circle inside the tube, with the larger circle flush against its end. Staple through the tube into the edge of the plywood to anchor them in place.
Cut 2-inch wide strips of corrugated cardboard. Wrap two thicknesses of these strips around each end of the pillar, against the plywood end to form a base and capitol. Staple them in place. Cut strips to length to run from top to bottom of the pillar, fitting between the rings you just installed at either end. Use a square to place these running straight up and down, evenly spaced around the pillar. Staple them in place.
Mix two parts latex paint in your choice of color with one part white school glue. Tear strips of muslin 3-to-5 inches wide and paste them to the outside of the pillar using the paint and glue mixture. Use a disposable paint brush to apply a coat of paint and glue, then spread muslin, then paint over the top with the mixture to adhere it. Overlap the strips and cover the entire pillar, including the bases and capitols. Allow the pillar to set over night.
Paint the surface of the pillar with latex paint to whatever color you want. Marbleize the pillars by using black, white and a jewel tone color. Blend the jewel tone and white onto the pillar with a wet brush, allowing the colors to mix freely, with some areas more white, some more color, with a wide brush and diagonal strokes.
Apply "veins" to the faux marble while the paint is wet. Use an art brush with a long handle to streak black and white across the surface, allowing it to blend. Stipple the entire surface with a sponge, while the surface is still wet, to give it a grainy stone texture. Allow the pillar to set overnight before using.