Starting with his ears, his right ear is the symbol for the "Incinerate" plasmid. Basically gives him fire at his fingertips to defeat foes. His left ear represents the "Houdini" plasmid, which helps him to teleport short distances. As for his head, I wanted to give Sander his face paint he wears in the game. I painted his face in a skin tone, then went over it many times with mostly subtle shades of white and grey. I wanted to give him really creepy eyes that stood out, so they were my focus for his face. Long eye lashes, runny makeup, and bloodshot eyes give this artist / showman that slightly disturbed look. Added a few blood stains on his face and on his gloves (from his dirty work).
Moving onto the suit, I based its coloring on a painting I have of Sander, by Robb Waters. I wanted to emphasize the flower on his jacket lapel, so I made it bigger than it should be. I also gave him a crooked bow tie, vest, shirt, and another bit of blood spatter. His shoes are the iconic two-tone style of the early 1900's. I figured he might like wearing a little pink.
For the back of his head, I painted a wooden bunny mask. Many references to bunny masks in the game, including his symbolic poem about not being able to take his off. Other Houdini splicers in the game wore wooden masks, so I thought it would look cool. Confetti surrounds his mask to represent the confetti falling when you first lay eyes on Sander Cohen in Bioshock. Also wanted it to be possible to turn his head around and make it look as though he's wearing the mask.
His back focuses on a mannequin (really a person forcefully covered in plaster) holding an empty picture frame on a stage. I made steps to the stage and also some nasty worn red curtains. The mannequin was part of Sander's work of art which he called his "Quadtych". It featured multiple mannequins holding picture frames that you had to fill as part of a mission in the game. And at the bottom of the steps to the stage, I gave him some bold red initials.
References and finished product: