I like the idea. I wish the uncommon placeholder parts like twig or screen changed more about the skin to really drive the "I wonder what will come out!". Scoring could also include some artificial connection to what you've created. Maybe a comment or objective judgment - "Oh, that's an interesting place for an eye" etc. Controls are a bit clunky. I see the potential in this with the parts getting gradually weirder. You could even tell a story like that. Creative idea!