what about a robotic arm able to write

[@Eric]

I'm thinking to build a robotic arm, or something like that, able to write, anyone can help me? 

[Alfa_Zulu]

so basically your pretty much looking at a cnc machine...

unless you can make the arm really strong and not bounce it'll be pretty difficult to make it write clear.

i'd google "CNC" or "DIY CNC Machine" there are heaps of tutorials out there so have a look and see what
you think 

[amando96]

so basically your pretty much looking at a cnc machine...

unless you can make the arm really strong and not bounce it'll be pretty difficult to make it write clear.

i'd google "CNC" or "DIY CNC Machine" there are heaps of tutorials out there so have a look and see what
you think 

6 axis cnc mill

[Selenaut-14]

I think that you'd have a better bet with a constant-speed car with a servo off the end with a pen trailing behind the car. You could program different motor sequences for different letters.

[@Eric]

Awesome, thanks.