this kind of optic fiber is probably only plastic so for a full DIY , you can use also fishing wire with a big power led or an old chistmass tree optic fiber lighted.....
@yoshida hi!
Im not sure where you get that #9 should be A5? Looks right to me. The pin is connected to pin 9, and that is D3.
For a rotary encoder, it depends on your input - but don't you want an analog signal in? In that case you use the analog pins.
Edit: offcourse, if you use a module converting it to digital like described in the the build section you use a digital pin.
