Strong, with well-developed brush hand can easily cope with the physical work, and with a hockey stick, tennis racket, paddle.
In the sporting goods stores sell special wrist bands: rubber “bagels”, spring and even air. But they are either “bland”, or only work for compression, and moreover, are not designed for the load change.
That’s why I made the expander, which has additional capabilities. And main from them — a gradual increase of the load by increasing number of springs.
The size of the projectile will depend on the width of your palm and length of fingers and the springs. But in all cases the pattern remains uniform. The base of the projectile U — shaped frame tube Ø 10 mm. Bend it in a known, pre-filled with sand. On the crossmember drilled several holes for rings springs. The other end of the springs hook over the ring on the plate is the bracket (made of anodized aluminum, brass, bronze with thickness of 5 mm) connected by two M3 screws which are covered by the spacer sleeve, with thumb strap (wood, PCB thickness 20 mm). Plate with the bracket form a single moving frame pair, which resist the movement of the springs (I took them from a clamshell). On the ends of the frame wearing a support handle (also wood, PCB thickness 40 mm).
1 — support handle, 2 — finger strap, 3 — bracket, 4 — frame, 5 — spring, 6 — ring.
This expander gives the different loads. Instead of springs you can use rubber band, threaded through the ring like lacing.
A. RYBKIN, Moscow
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Recommend to read ELECTROCITY Somehow I read in your magazine the article "rainbow on aluminum" and remembered a very convenient way of drawing figures and inscriptions on metal. Brush for these works is a glass tube... SIMPLE EXPANDERS Strong, well-developed hands — the dream of all guys. The range of remedies that strengthen the hands, is huge. To hand firmly held a hockey stick, a tennis ranetka, easily controlled... 
Strong, with well-developed brush hand can easily cope with the physical work, and with a hockey stick, tennis racket, paddle.