I am sold on the impact drill for confirming impact alignments of the FLW and the bent right wrist. I just ordered an inexpensive impact bag at TGW/Amazon and wanted to get the info for dowels. I remember seeing that the dowels should be 5/8 " thick, but I have seen some posts suggesting squared dowels....is this important? What length should the dowels be for the drills?
I use two types of 'sticks' to do my 'tricks.'
The first is a round dowel -- 5/8" X 48". The extra length is important because you'll perform your drills gripping down on the shaft a distance about equal to the entire length of your Left Forearm. This promotes Left Wrist stability and a real sense of the Left Arm Flying Wedge alignments.
The second is a four-sided sign stake that is shorter and gripped normally. I use this to heighten the visual and kinesthetic sense of 'Aft' -- behind the Shaft -- Pressure Points (the Left Thumb, last three fingers of the Left Hand and pad of the Right Forefinger).
I sometimes use a third stick -- a four-sided balsa wood dowel -- along with a balsa wood board to demonstrate the Left Arm Flying Wedge alignments. However, these are Instructional Aids and not Training Aids.