In all honesty, it took WAY longer that 90 minutes as it measures 14x17". But this thing is neither a 'commission' nor a 'sketch', so the best classification I can come up with is '90 minutes'. Add to that all the damned hatching to emulate the digital/polygonal effect for Sam and design elements in the background, and it's safe to say that it took way longer than it should.
Also, before you crazies start in with the e-mails about specific inaccuracies in regards to this TRON: LEGACY inspired image, let me just say this first:
"I KNOW THAT IT'S NOT 100% ACCURATE - YOU OVER BEARING, OVER CRITICAL, SAD SACK OF A MAN! GET OFF MY JOCK!"
The reference you can find online were a challenge to decipher, so I did the best I could in interpreting them for this image. You're just going to have to deal with the liberties I took, and I guess we're just going to have to do what we can until the movie comes out during the winter season.
Until then, you get my jacked up version of Tron. Enjoy.