Hand Exercise Toys for Repetitive Strain Injury

Boading Balls

Those metal/stone balls are called Baoding balls. It's Chinese tradition for hand exercise. It's relaxing to rotate them. Sometimes when i take a walk in the park, i carry them and rotate them.

For buying advice, see Chinese Hand Exercise Ball

Hand Exercise Putty

Hand Grip

Rubber Band

Get a rubber band. Wrap them around all 5 fingers, then try to open the fingers. This is kinda reverse exercise to squeeze balls. With the right size of rubber band, you can easily expand your fingers once every second.

Juggling ball and Squeeze Ball

Get a squeeze ball. There are several types of squeeze ball. Some are spongy and light weight, requires little effort to squeeze, and spring back into shape immediately. Another type feels like clay; You have to squeeze hard with the whole hand for it to deform, and they deform slowly. I like the clay type better.

It is universal advice that you should have AT LEAST 10 minutes of break every 2 hours. The exact schedule varies. I always take breaks. Some people use a alarm clock, but i tend to do it spontaneously. Every 2 hours or so, i'd get up and walk for 10 minutes or do some juggling during break. Been a juggler since age 17. (See many juggling videos at Juggling and Performance Arts.)

Pen Twirling

Xah Lee Pen Spinning

You might try to pickup Pen Spinning. Though, am not sure this is good for you. Learning the tricks can be addictive, and the constant pen dropping can be quite annoying to those around you. (In East Asia, majority of highschool students do some form of pen twirling. When walking into the class, you hear the sound of pen droppings all over.) Pen twirling has become a unconscious habit for me since age 13.

See also: How to Avoid Emacs Pinky