Advice on building a table?

This spring/summer I'm going to make a Kotatsu. The thing is, I want to do it a little differently and make it round (or octagonal) if possible.





My question is this: Can I do a square base and build on a base to fit the top? If so, how would I go about doing it? I have a few ideas but any advice would be appreciated.Advice on building a table?
You can do just as you say. Build the top any shape you want as long as you put a square base on it that will fit over the bottom base.Make sure you center the top on the base.Advice on building a table?
Not sure what your question is. From what I can tell, a Kotatsu is basically a box with a top on it. I would think you could make any sort of top you want and fasten it with table top connectors (which allow for wood movement, which you will get if you are using it to heat.)