origami folding and crease marks in paper

Hi,  

I am trying to animate a piece of paper into an origami fish.  I am using the AnimAll add-on and that is working great.  Currently I am using a plane with the solidifier modifier to make the paper.  I would like to show a crease in the paper when you fold and unfold a section, but am stuck here.  The only way I can think to do this is to bevel the edge and then animate the crease to show up or maybe use a shader and animate that to show the crease after it is unfolded.  I would rather not bevel the edge, I think the geometry would get really messy fast.  Does anyone have an idea of how to this?  I didn't have much luck with googling it.

Thanks.