Here things are set out for our block.
Here the posts have been attached for the outer and middle borders along with the centre square-in-a-square.
Apparently I missed a picture of adding the middle border, but I then added the middle border and then the outer border to complete the block.
If you're adding the extra seam allowance to the border blocks, you'll want to follow along here.
First I attached the triangles for the centre rectangles and posts for the remaining borders.
The middle border has now been added.
And finally the outer border to complete our next block.