Some of the best uses for 3d printing are the simplest.
My favourite sunglasses were gripping my head a little too tightly, giving me a headache. So I sanded off some material around the hinges, to make the arms open wider, but oops! I took off too much plastic on one side! That meant they didn’t fit tightly enough, and one lens was really close to my eye. Doh.
What to do? Those were expensive sunnies. I needed to insert back exactly 1.6mm of material, cut to the right shape.
Five minutes later I had designed what I needed in Google Sketch-up. It only took a couple of minutes to print the part, since it was so small, and I super-glued the piece in place. The colour is not perfect, and I could have spent more time designing the shape to fit exactly, but it works great and it was super-quick.
Google Sketchup is free for home users, and you can learn the basics in under an hour.