This self-help device can be helpful for writing with a ballpoint pen. It is not only light and easy to wear, but also possible to use the commercially available pens. Mount the pen in the holder chuck and attach to your finger. Easily can write with lateral motion and slight rotation of your wrist as shown in the video. Also fit in right or left hand. It is recommended to use the pens having a rubber grip.
Caution: The use of pens with diameter of more than 11 mm will cause damages of the chuck.