Mix food coloring with a T or so of water into individual ramekins. You can do any color combination you like.
Add a couple T of mod podge into your mason jar
Add one ramekin of color into the jar and stir to incorporate it all together
With a bowl underneath, carefully twist the jar around coating the whole inside with the mod podge/food coloring mixture. Pour the excess out into a bowl.
Let dry upside down on the paper
Do the same with the other colors. Let them dry for about 30 minutes this way.
Place the jars face down on top of wax paper and a cookie sheet into an oven, set on warm. Let dry upside down this way for about 10 minutes and then flip them over and let them dry another 20-30 minutes.
When they're ready, they'll look clear and the mixture should lose most of its streaks. If there are streaks left, continue to let it dry out in the oven. The pink one above I put back into the oven after seeing those streaks at the top.
A gorgeous set of deocorative mason jars for flowers or plants or illuminated with battery operated tea lights for an outdoor party (but not safe to drink out of anymore).