Altouhgh I wasn't going with the intention of getting koozies, I found a purple and a pink sparkly pair and couldn't say no. Not that they need much jazzing up but I wanted to personalize them a bit more. I had puffy glitter paint and decided monograms would work perfectly.
Here's what I started with:
Step 1: Find a font you like and practice writing it in a size that fits the koozie. (I chose this font)
Step 2: Once you have that down, draw it onto the koozie in marker (I used permanent which ended up sorta messing up mine, but the one for Heater came out great!)
Step 3: Use the puff paint to follow the letters and voila!
As you can see mine (the one one the right) ended up slightly less awesome than I had hoped. But really, when everyone's drinking no one will notice!
These are really cheap, and would be great for a bachelorette, bridal shower or as part of a summer gift basket.