I kind of showed this in this post here, but I never went into full detail about it:

I had ideas on all of the animatronics, except for Freddy himself.  So I hastily whipped up something that I’m rather ashamed of and I’m planning on adding it as a joke easter egg.  It was absolutely terrible and flat out ugly.  I tried making it just a kid with a Freddy head on to indicate how this is supposed to be weak, and not as aggressive as the others, but it just came out horribly.  Since the designs are supposed to visually represent how the children died without having to tell the player, I ended up becoming very worried about this design.  I couldn’t scrap it immediately though as I had no better ideas for how to design him.  I eventually did though, and thankfully was able to replace him with something better, and I can’t wait to show you the new design soon.