I couldn't believe the outrageous retail price of an "electric finger" when I looked for a stylus for my iPad.
All similar "capacitive" touch-screen devices work in much the same way, so I made a zero-cost, quick 'n dirty stylus, just to see how it behaved. It worked well and I saved a chunk of money too.
You will need
-- a discarded metal-barrelled pen (or propelling pencil).
-- a thin softwood skewer (think kebab / barbecue).
-- conductive foam (source: computer repair shops, most people throw this away. It's what microchips are shipped in).
-- Rip the guts out of an old metal pen.
-- Keep only the hollow metal tube.
-- Cut a length of the woooden skewer to fit right up inside the closed end of the metal tube, leaving about an extra 6mm (1/4 inch) sticking out of the open end. Smooth the protruding cut end to a rounded, blunt shape. A nail file works well.
-- Cut about a 25mm (1 inch) length of conductive foam, wide enough to cover the wood generously on each side. Scissors are safer than craft knives. You are aiming to simulate a finger pad in size and shape. Keep all your fingers!
-- Fold the foam equally around the end of the wood.
-- Squish, mould and gently persuade the foam plus wood until it fits tightly inside the writing end. The tighter the fit, the better electrical contact it will make. The touch screen needs to "see" your writing fingers "through" the foam and metal.
-- Start writing / drawing with your new stylus.
1. Replace the foam when it wears out. With normal pressure, the soft wooden "stiffener" should not damage your screen if it breaks through the foam before you notice the wear and tear but I advise using a screen protector at all times.
2. Yes, there are plenty of other DIY stylus designs here at Instructables, so go and look at them, then take what works for you and make something yourself. That's really the essence of the spirit of this place and is what I most like about Instructables.
3. Markerickson uses a Q-tip (cotton bud) as a support in his design.
My thanks to Dan Bricklin for his excellent app "Note Taker HD", the handwriting features of which inspired me to make a stylus.