I recently bought a water bottle made from pure copper. It makes the water taste better (I drink tap water), and should last a very, very long time. Much better than plastic.
I made a radius tester yesterday to figure out the radius of a corner i need to model around. After printing it I realized I could just use math, but that would require a metric L-Square which I don't have (why are metric tools so hard to find in the US?!) and math. Math and I aren't friends.