Months.. sure this took months!! You're lucky no teacher ganked this on you! A lot of bored kids do the same sorta doodles, but the consistency of this work is extraordinary, especially given the time period involved!! And no ink spots either (unless you inked them in). I spy a touch of black ink... What kind of pen did this? I prefer a Pilot G2 very, very fine point meself, but even that one gets a bit sloppy, if you're not careful :)
How crazy would it be to color this digitally? A most excellent piece.