How it's done
At the time I did all these Marvel and DC pictures, I was learning Poser and postwork. I felt the best way to learn would be by setting myself challenges: that way, I couldn't let myself off the hard parts. So, I made this series of cover images featuring existing characters I'd had to put together for the purpose.
3D against 2D
Translating these characters and costumes into 3D, I had to make decisions about how they'd be constructed and textured. I went at the time with a fairly padded, Frank Miller-style Batman, a Superman vaguely modelled on Christopher Reeve (who'd just died at the time, I think), and a Spidey who could conceivably have made his own costume. I also re-styled some of the costumes a little, incorporating some leather into Daredevil's, and lengthening the Martian Manhunter's trunks (a change I still like and would probably make again).

And this is still Iron Man's "real" armour...
Click on these to see them larger.
 
Samples, proposals and finished pages.
 
Sketchbook (yes, that is Byrne art there).
The Links: