Pasta is strange. Think about it, what other food do we sell in that many shapes? Wikipedia lists 163 different pasta shapes but claim there are over 600. Where did they all come from?
I'll put my radiatore on some Italian spiralini that was making macaroni art one day and thought, "Does anyone realize that instead of making Mona Lisa's 'tache out of curved 'ronies, we could shape them into little dinosaurs and market them to lazy American college students?" And you thought the internet was big.
Dinosaurini - Little Dinosaurs
Seriously though, once you've hit about 30, you can probably stop making new shapes. Silly straws knew when enough was enough. How many shapes of one thing does a person need?
And how do you come up with new shapes? Who looks at a list of 599 pasta shapes and say, "No, wait! This one is going to change it all!" I now present to you the true story of shape 391:
It was 4am and the stars were hidden behind a thick black fog. Hank stood alone in front of a chalkboard, hands cracked, hair full of dust. He closed his eyes, lifted his last stick of chalk to the cold slate, and sneezed. When he opened his eyes and saw what he had done, he knew this was it. This was the shape that would finally put his name on the blue box in isle 6. This was Lumaconi.
Turns out, that's also the story for about 200 other shapes, just replace sneezing with any other quick, jerky action (Masturbatoni?). The rest involve heavy drinking (Jägeretti), flour and water.