I made this awhile back and use it all the time. I also did a class at a LQS on it so I have some directions as well and put it out as a tute (there is a pdf file under the photo for download). It is larger than what you showed but it works for me!! lol
http://www.quiltingboard.com/tutoria...al-t38958.html
I have also included some pics of the one I have