LEGO is a big tease when it comes to round pieces. There are some sizes that are offered and some that seem to be strategically left out. Now I understand that LEGO goes light on the 3 stud dimension but some things cannot be cobbled together and need that specialized piece. There is a 1x1, 2x2, and 4x4 round plate. I present to you the 3x3 plate to fill the void. This plate is unique in that the stud pattern on top does not match the stud pattern on the bottom. If you want to create a 3x3 round stack then the studs fit nicely inside the tubes of the next piece. No problem. The reason I suggest this is because otherwise you end up with 5 studs on top in an X pattern which I feel is less usable.
Now I realize that there is a 3x3 technic plate already but have you tried stacking those? You need to pass an axle through and it certainly does not leave a smooth surface. Great for a disk plow, not so great for a column.