Okay so all you need to do is double that measurement, so I'd cut 2 squares at 6" and layer rightsides together and mark with an "X"
Now sew a quarter inch away from those lines on both sides, like so...
Heres the tricky part, cut an "x" like this first
And now cut on the lines you made and you have 8 HST's! Isn't this just peachy! I made 96 HST in less than an hour!