A plunge router is just about the handiest tool to create flutes in columns. So if you already own a plunge router accepting 1/2" or 12mm shank bits, it should serve you.
Round columns will require more than one fixture or jig. You will need the function of a large lathe, so you can rotate the blank column on its center axis, and at the same time indexing it so that the flutes are evenly spaced. Then you will need a fixture more than the length of the column to support the router. That support needs a central slot, which ideally is adjustable for width.
A guide bushing is attached to the router. The slot width is adjusted so that you make one side of the flute going in the normal direction, then index from the other side of the slot to make the cut on the other side moving in the opposite direction. This is a task best done without a guide rail, since the router needs to be supported on both sides anyway. A flute is another form of dado, which are best made in two passes, so the climb cut is never a final cut.
One MFT/3 will not support a column longer than about 3 feet, but even a single full-blown MFT/3 is darn useful. MFT/3 are ideal in a set of three, with only one fully loaded.
Many of us who have made fluted columns for decades often have dedicated metal stands taking the place of the tail and headstock of a lathe. But others make those so they attach to a sawhorse at either end, the legs adjusted so the top of the long fixture is a comfortable height for you.
You place a stop at either end of the slot at the desired length of the flute. Trust me, it save a lot of effort to let a plunge router rise at the end of a cut instead of lifting the whole router!
BTW, in my opinion, this is a task where the larger OF2200 is no advantage over the lighter OF1400.
