I'm not sure what happened for me with this block. If you look you'll see that my three smaller blocks on the outside are all consistently too large.
I put on my liberated hat and just sewed it together.
It ends up 10.5 square, so I'm happy.
I forgot to invite you all to join in the Liberated Round Robin - you might be interested for a little change of pace.
It's a summer project. Guidelines for adding rows will be posted every three weeks.... So there will still be time to do the FBP!
This block could be both the initial center block and the first row as they are triangles!