That's awesome. I was thinking of doing the same thing. Thanks for the picture.
I haven't tried the cup holders but there is a company that makes an ash tray cup holder insert that holds one big drink instead of two can size holes.
I don't smoke so I cut the upper screen type thing and the little hook in the lower corner out of the ash tray. Then I sprayed the inside and the part of the outside that you see with Plastidip. It makes a great place for my iphone (or whatever). Plastidip is a very cool removable rubber...