You are totally right! The last two are really mostly to get a sense of the thickness. I didn't have time to mess too much around in fusion 360, i just wanted to print something while i were by the printers.
I'm liking the first one as well, as it fits very well in the palm of your hand. It is actually really nice just to sit there and fiddle with it. So i think my next step is to make a silicone mold, and cast a couple of them in resin.

I love your cog idea, i will definitely think about implementing that! Thanks a bunch mate :)