My first, and probably last pair of mittens created this way. I used a flat warp and cut it near the middle to create two mittens from the same warp. The thumbs were created similarly from a much smaller warp. After tying the fringe at the cuff I nalbound a few rows to hide the knots. The thumb joint is bulky with knots from the the small piece's fringe.
If I make another pair of mittens they will be more like the pattern shared by Carol James.