Ball Stylus can be customized for ball size, stylus length, and surface smoothness.
This stylus was designed for people who have difficulty extending a finger to operate a tablet, and have difficulty gripping a standard stylus. It is printed with conductive PLA from Protopasta.
For more information on assistive technology, visit http://www.rehabengineer.com, or our agency at http://rehab.alabama.gov/ .
I reduced the infill to make the stylus lighter. I suggest printing on painters tape so the bottom doesn't peel off on the bed when you go to remove the stylus from the print bed.
You will need to add a piece of conductive foam into the end so that this stylus works better with capacitive touch screen. You can use the foam the IC chips are embedded in, but I have found that a fresh, never used Scotch-Brite® Non-Scratch Scrub Sponge works well as conductive foam. Just cut the scrubby part off, and cut a 1/4" by 1/4" by 1" chunk off the sponge. Once inserted into the stylus, trim the sponge so about 1/8" is sticking out.
New twist on old design
For decades rehabilitation engineers, occupational therapists, teachers, and other allied health professionals have been making modified styli by punching a hole through a tennis or racket ball to make it easier to hold. This updated design uses conductive PLA so that the ball stylus will work with a touch screen.