I love the 3D design process! The usefulness of being able to design and print something to exactly fit a need is one of the coolest ideas ever!
I love designing things for my motorcycle, my 1972 MGB, or any of the other various projects I always have going on.
I also sell some of the 3D prints I've designed over on my Etsy store.
I can print and sell any of my Printables models with the “custom order” button on Etsy!