I made the columns by milling 2x4 by 10 foot pieces on a table saw down to ¾ inch thick strips and filling the gaps with ¾” wide flat moulding pieces (actually I mostly milled these from the 2x4s as well, but you could buy them as is). The pieces are nailed and glued to semi-circular segments of pinewood that form shelves behind the roundels. Some extra thick edging pieces at the ends provide a secure place for mounting piano hinges. The hinges come in 48” length so because the walls are 9 feet high, I put up with a 12” unhinged section at the bottom of each. You could cut the piano hinges with a hacksaw if you don’t like that.
There are seven columns in my Tardis, all of custom sizes and they all hinge and contain shelves.