This reflex tool may be considered “the poor man’s double-end bag.” If you are not familiar with double-end bags, they are excellent for developing agility and timing for strikes. With one end attached to the ceiling and one to the floor, the double-end bag “bounces” back and forth quickly with the strikes, allowing for practing not only strikes but also dodges. A device with similar reflex developing benefits may be constructed very easily.

Simply select a small stone (half pound or less) to serve as the core of the "ball" and wrap it tightly in a plastic bag. Next, wrap the plastic bag tightly in a paper bag, wrapping the entire ball with packaging tape as tightly as possible. The entire ball should be approximately the size of your fist. Hang the ball from the ceiling at head height, preferably with a "springy" string. When striking the ball, it will move around relatively sporadically around your head (due to its rough shape, compared to a predictable tennis ball). Practice moving around the ball while striking it, allowing it to swing out and dodge it to develop reflexes. Allow it to swing behind your head, so you may practice evading strikes from behind (wait until the last second, to develop brisk reflexes vs. ‘leading’ the reflex action). Continued use of this reflex exercise will also work wonders toward spatial awareness of your entire body (around your head, torso, sides, back, etc) in addition to developing reflexes.

Although not as “bouncy” as a true double-end bag, the reflex “ball” you have made has the advantage of being able to swing behind and arc around your head, unlike the relatively straight linear motions of the double-end bag. Additionally, lacking a floor anchor, it may be kicked easily from beneath; allowing you to work on your kick reflex.