For those of you who do projects that you mod podge but need water proof (like for outdoors or coasters, etc.), what do you use? i know there are waterproof sprays and other things out there, but i wanted to check with you crafty ladies before i picked. I am planning on doing some of those scrabble tile coasters as a gift for my mom and my grandma (they are scrabble nuts!) Both their birthday are in the fall, so I am planning ahead big time lol!