When I was a kid, coasters seemed like something to whip at my siblings, ninja star style. Or to stack like a house of cards.
Then I became an "adult", got a glass coffee table and was forever cleaning circles of coffee and condensation. I then realized the importance of the coaster. So we made some out of leather, using thick 9-11oz cow hide (which is 1/4" thick give or take), and simple shapes. These elevate any morning coffee, and are still fun to throw at one another.