I recently painted up this Iron Warriors Daemon Prince as part of a commission. I decided that I really wanted to add a little flair to the mini as a whole- so to make it stand out on the battlefield he has a nice customized base.
The base is simply green stuff over a normal base. Carving a chaos star into it is simple enough. After that, I painted it exactly the same as I have with lava cracks (including the Object Source Lighting from the ground).
The conversion is partly my work, and partly the work of my client. The mask was taken from a Defiler, while the hammer hand comes from the Cygnar plastic warjack kit (Warmachine). Altogether, I think he achieves the half mechanical look needed for the Iron Warriors.
Anyway, enough talk: