Here are a few of the pages from the huge anniversary issue I was able to take part it. It was also my last issue on Detective Comics as I am now moving to Batman: Eternal which launches this spring.
I also got the chance with this story to design some cool alternate universe costumes for some of the characters. Here's a look at Batman, Catbird and Bluebelle.
With Batman, I wanted an all white version of the suit, but realized I needed some greys to break up the different parts of the suit. I tried to add a bunch of cool textures and details to the suit to give it a different feel from the normal Batsuit, and also made his eyes visable.
With Catbird (Catwoman as Robin) I originally was going for more of a Catwoman/Nightwing crossover. But we decided we wanted it to be more Robin-ish. Above, you can see the idea evolve to the final chosen idea.
I wanted to keep the Catwoman look, but incorporate the Robin aesthetic into that. The long jacket I felt took the cape aspect of Robin and fused it with Catwoman's sense of design.
Bluebelle is the Gothtopia version of Batgirl. In the end, I mostly took the New 52 design and made it white. I shortened the cape to give her a more playful, youthful look and got rid of the cowl. I actually prefer Batgirl to not wear a Bat cowl. I'm not sure why.