I took a screen shot, to show the block.
[ATTACH=CONFIG]438405[/ATTACH]
It's a 16-Patch (4x4), so if you want the finished block to be 12", divide that by 4 and you get 3" for each finished (after seams) small block. That means you need to cut the small corner blocks at 3-1/2" x 3-1/2". For the HST blocks, you'd need to start a bit larger, to allow for the diagonal seams.
Best bet is to make a sample block, with scrap fabric.