Here is the magic square that can be created using the hidden square from last week's post:
Notice that the onion rings appear on the inside of the square. In the previous magic square (lower left in the photo below), the onion rings are on the outside. Each time the magic square is built up to a larger size, the onion rings will flip (from the outside to the inside, and vice versa).
If you look at the large square, you can see several of the smaller squares within it. Using the same basic repeat, the pattern can be built up to any size, all in one round.
I won't be tatting any larger squares as I'm just using it as an example of how to design a magic square. I should have more detailed posts about the process in the next couple of weeks, and will also be sharing the pattern on my blog.