I finished these off last night. They’re not quite identical – I cast on at a slightly different place in the black of the colour progression, so one has more black on the bottom and the subsequent colours are not in the same spot from one to the other.
I used Amanda Gill’s free fingerless mittens pattern and adapted it (as I did for my sister’s wrist warmers). I cast on 52 stitches and after 2.5 inches of 2×2 ribbing, I gradually decreased down to 45 stitches, then continued on much as the pattern directs except the length before beginning the thumb gusset was 9 inches. The thumb was done on 16 stitches for 5 rounds.
Once they were done I picked up the ruffled cardigan and worked a few rows on that.