Yesterday I finished the thumb gusset increases on both mittens then knit 6 rows without increasing. This results in 70 stitches total, 20 on the side needles and 30 on the thumb needle where the markers are.
The next round, I work up to the first stitch marker, 3 stitches in.
Using a simple cast on (making a backward loop with my thumb) I make 7 stitches, the same number that I marked for the increases just above the cuff. Try to make the cast on stitches fairly loose as once the hand is done, these cast on stitches will be picked up and knit along with the stitches between the markers to complete the thumb.
Next I thread a tapestry needle with nylon yarn, one of the few times I prefer a synthetic. A smooth, strong thread, such as crochet thread also works well, or you can use commercial stitch holders, safety pins, etc. Some people prefer to use a strand of contrasting yarn, but I have found that especially with fuzzy yarn, some of the threads can be left behind. It doesn't affect the structure, but isn't as attractive.
I transfer all the stitches (17) that were between the markers onto the white nylon yarn.
Next I remove the tapestry needle start to knit up the 10 stitches left on the thumb needle.
Here I have knit around and am knitting the cast on stitches. This is a good time to get a count to make sure everything is OK.
Here the left mitten is folded flat after knitting 10 (half) the stitches on the thumb needle. This is the shape the mitten will take after the top is closed.
Top view of mitten on my left hand, thumb stitches left on the strand of yarn until the rest of the mitten is completed.
Bottom or palm side.
Now I will take off the thumb stitches for the right mitten, then on both start knitting the hand stitches.
This part and the cuff are the two fairly mindless parts of knitting four needle mittens. This is a good place to put in a knit and purl pattern, perhaps the recipent's initials, or a couple of cables on the back of the hand if you want some excitement. To add color patterns, put the more elaborate patterns on the back half of the mitten, then do a smaller pattern such as a simple checkerboard on the palm half where wear will be heaviest.
Check back tomorrow!