Regardless of your Political stance, one thing is for certain... the Inauguration gave us some of the BEST memes, and Bernie's mittens totally stole the show! The story is that they were gifted to him from a Vermont school teacher who repurposed old sweaters into mittens, and lined them with fleece. How very Vermont (& I love it!).
If you happen to be crafty, you could probably pretty easily copy this format of mitten making on your own without need for much tutorial. You may run into a little trouble finding the exact sweater to use however, if you want these EXACT mittens. Can you knit? If yes, here's an even better option for you! Alyssa Coffey of Al Co Knits on Ravelry, a popular site for knitters & crocheters, created a FREE tutorial called "Bernie's Mittens"... follow along & make your own sweet mittens at home!
Unfortunately, I am not a knitter, but I do know how to crochet. Yes, there is a BIG difference (#iykyk). I couldn't find any mitten patterns (yet) on Ravelry, but click here for some cute dolls. You could also check Etsy to purchase a crochet mitten design if that is your craft of choice.