Thankfully, I took the risk and went through with this book. I was really never a fan of sci-fi books. (I love watching sci-fi movies though) I read them but I never quite finish up since I'll be turned off by things that I can't quite picture out. I was kinda slow in reading the first half of the book since there's not much going on and I'm reading the hard copy of Cinder while reading the ebook of Easy by Tammara Webber and my attention was more on Easy so I finished it first but I finished the second half in a matter of hours. I really like it. 
 My week was filled with sci-fi actually since I had a X-Men movie marathon and watched Guardians of the Galaxy so I was like in the zone for this kind of thing. 
 What really helped in picturing Cinder though is my old fascination with the Terminator Series and for Cinder's cyborg programming messages I just imagined it to be something like Iron Man's. Haha. I dunno. As long as I get the picture. 
 As for Iko, Star Wars helped me on that part. I just imagined R2-D2 to have a girlish and stylish side. I will really like it if she will come back in the next books though. 
 For Prince Kai, even though he was supposedly Chinese (right?) I can't help but picture him to be an anime-like Japanese prince with all those black fringes falling in his eyes (lol!) 
 Kinda like Yuuri Shibuya of Kyo Kara Maoh (he is also a teenager king!) 
 I agree with Marissa Meyer's answer for which character I most identify with myself. It is evidently Peony. Haha! I dunno any mechanic stuff since I'm not a fixer of tangible things and I will propably pine for Prince Kai, and be giddy to make it to the ball to witness his jaw-dropping gorgeousness. 
 I want more Cinder-Kai interaction in Scarlet since their love story has been cut-short by Queen Levana and I hope that they will still have their own point of views even if there will be new set of protagonists :)