You'll need 2 skeins of worsted or aran weight yarn. I used Twilley's Freedom Spirit (worsted) and Classic Elite Wool/Llama (aran) they are each about 190m/205yds or more. I used about 7/8ths of the Freedom Spirit skein and 3/4 of the Classic Elite skein for women's medium mitts. Mine are fairly narrow and long so they just fit my hands.
I used 4mm needles on the hand and 2.5mm on the thumb. I would have preferred a more tightly knit fabric though since I can feel the wind a bit. Once the inside felts with wear they'll be perfect though so no worries there. The windy part may also be that the Twilley's is so much lighter in weight than the Classic Elite and if I had used two aran weights I might not have this issue. I didn't take gauge so you'll have to go with a gauge that will fit your hand. You can do a gauge swatch and the math or you can just start knitting and try on as you go. One guess which route I took.
I used a generic mitt pattern that was divisible by 4 (cast on 40 for my hands) in colour A. Knit the cuff as long as you like in 2x2 ribbing or whichever stitch you prefer. My cuffs are fairly long. I really hate it when your sleeves move a bit and you get that gap at the wrists.
When you get to where you want your hand to start, add colour B. For the first row of the repeat you will be stranding and the following two rows you will be mosaic knitting. If you are making a thumb gusset, you will need to increase by four stitches on each stranded row (I made mine 12sts) in order to maintain the pattern. I also cast on 4 in the row above my thumb to help with the laddering above the thumb gusset stitches and to keep it nice and loose there. If you are not making a thumb gusset, you'll need to increase a few stitches (again, divisible by four) just above the cuff to help the mitt fit your hand better. You can do this easily on the first round of the repeat once you've added the second colour, or you can just knit a plain round right after the ribbing and add them evenly then.
Row 1 - Colours A & B - K2 with A, K2 with B. Repeat to end of round.
Row 2 - Colour A only - K2, S2. Repeat to end of round.
Row 3 - Colour B only - S2, K2. Repeat to end of round.
Row 4 - Colours A & B - K2 with B, K2 with A. Repeat to end of round.
Row 5 - Colour A only - S2, K2. Repeat to end of round.
Row 6 - Colour B only - K2, S2. Repeat to end of round.
Repeat Rows 1-6 to desired mitt length from base of hand to tip of fingers. Follow a generic thumb pattern for either a gusset or an afterthought thumb. That's about what I did. The colour pattern will blend on the hand no matter which route you choose as long as your thumb stitches are divisible by four. That way it doesn't interrupt the pattern on the hand.
Once you are at the top of the fingers, you will need to decrease by four on each side of the hand every time in order to maintain the look (total of 8 sts decreased each round). Best done on the stranded row in order to make things easier. I did this three times then Kitchenered the last 16 sts. I think next time I would finish the last repeat before the decreases (I did 9.5 full repeats) and seam the top since the Kitchenered top lets in a good bit of wind and a seam would be more solid and therefore more wind resistant.
Weave in your ends and all that stuff once you've finished and voila! For once, a Changeling a mother would love to have gotten.
My little sweet loves her new hair by the way. She still asks when it will grow back, but then she fluffs her sides and declares that her short hair is so pretty. Naturally, we agree.