Take one of your mason jar lids and using your pencil, trace it around the cork and cut. Repeat for each coaster you plan to make.
Lay your cork circles on some parchment paper and using a brush, paint an even coat of paint and allow to dry completely. I suggest at least 30-60 minutes. If the color isn’t solid as desired, apply one additional thin, even layer and allow to dry COMPLETELY! At least 60 minutes, or even overnight. If not, your ink could streak.
Once your paint is dry, apply a solid layer of ink to the stamp. Center the stamp onto the cork circle and press and hold for a few seconds and lift. Although this says waterproof and permanent, you still need to let this ink dry COMPLETELY before moving onto the next step. We waited 60 minutes.
Using a clean brush, completely cover each cork circle with a thin, even layer of Mod Podge and allow to dry completely (I suggest at least 60 minutes). Be sure to coat both sides. I suggest giving each one two coats.
Plug in your hot glue gun and allow it to warm up before using. Using your hot glue gun, attach each of the cork circles, stamped side up, to the inside of each of the mason jar lids. Wait about a minute and you now you are ready to enjoy your new DIY Stamped Mason Jar Ring Coasters!