Just got Kreg's Box-joint jig. I had some 3/8th Poplar and gave it a try. Things go much better when watching their included DVD. Written directions are lame and sparse. Fingers are nice and snug and there is even a guide that calls out the amount of tongues depending on the width of wood. This was a test piece of poplar so surface was kind of boring. Gave it to my wife for her artistic touch. The lacquer finish made the excellent painting pop!