Mason jars are sturdy, cheap, and make interesting glassware if you’re going for a country or hipster aesthetic. By drilling a hole in a jar lid and adding a rubber grommet you can also convert one into a tough spill proof cup.
It’s also great if you’re one of those parents who avoids plastics or if you need a way to carry your DIY Frappuccino. Household weblog Little Bit Funky notes that all you need to do is drill a ⅜-inch hold in the lid, slide your grommet in the lid, and perhaps run it through the dishwasher a time or two if any residue is on the grommet. The grommet should fit a standard drinking straw.
How to turn a mason jar into a spillproof cup with straw (for ~50 cents or less)! | Little Bit Funky
via Lifehacker
http://lifehacker.com/5951280/convert-a-mason-jar-into-a-spill-proof-cup