Cycles Cell Outline

Description:

It's not an instant outline.

Enter Edit mode, Select All, Duplicate (Shift+D), Esc, Alt+S (Scale along normals) - choose a thickness of your outline here. Go to Vertex Groups, create one, Assign current selection, rename it to Cell (use it further to select quickly), Invert Selection, create another v.group, Assign.

Now go to Materials, make your own Diffuse or Glossy material (this node setup works bad with Glass) or choose from mine (there are comments made with Grease Pencil), assign appropriate materials (Cell is a bigger mesh if it's not clear ;) ).

Some versions of setup works better (more intensive shader) but has some weird limitations. Play with them and you'll see it.

P.S. I got this idea from some video on YouTube. Thanks, dude :)

Ppl, credit me if you want... or not - your choice :D