I created this little guy a while ago. I don't remember the base figure. I made Spawn's cape from two capes of other mugg figures. The top cape was cut, and then the capes were inverted, hot glued together and then I added Aves Epoxy to smooth out the seam. Weapons and ammo belt were from GI Joes figures. Bands are made with Faux leather (sewed on velcro to connect) and craft store spikes and chains. Skull on belt was sculpted.
I was having a problem at first trying to get the symmetry right with the eyes and white area, but I solved that by creating a template using some plastic template stuff that I picked up at a craft store (I think I found it in the stenciling area, but you can use any flat piece of plastic that you can draw on or paper if you want. Since I wanted to be able to use the template again, I went with this stencilling plastic, because it's more durable). Once I drew out the design on the stencilling sheet, I used an exacto knife to cut it out and then I taped it onto the figure and drew out the design. I then took it off and flipped it over and tape it down for the other side of the face, making sure it looked symmetrical. It's a little awkard, because you have a flat piece of plastic and a round head, but if you do it in pencil, you can make adjustments after you remove the template and then once you get it right, you can go over the pencil with a marker. The final result turned out great.