He posts at universalhub.com about the brand new CharlieCard Mitten designed by the Subway Knitter. who tells all how the idea came to be.
Without further ado, and just in time for today's cold snap, I present to you the Amazing Charlie Card Mittens! Those of you not from Boston might need some background. The T has recently completed an upgrade to its fare-collection system. Gone are the days of T passes and tokens. Starting in 2007 we're using a new system of rechargeable stored-value cards. I guess that it's a lot like the Oyster card on the London Underground. The cards are passed close to a card reader mounted on the front of the turnstiles. For those of you who don't know, you need not press the pass directly to the card reader. It just needs to get close to the reader.
"Ah, ha!" you're thinking. Exactly! Why not store the pass on my right hand, so that when I get to the turnstile I need only to wave my hand in front of the reader (located on the right side of the turnstile) to gain entry? Why not, indeed! So, when I finished knitting the mittens, I measured my Charlie Card (about the same size as a credit card) and knit a pocket for it that's slightly bigger. I knit a flap and attached a cute button. Now you might understand why it was so important for me to keep these mittens from getting lost, and why I knit the string to keep this pair in my coat.