Here's a WIP to cure the blank page! It will probably turn into a headband for when the weather stops being 30°C and starts being -30°C. Hope to see more people come along shortly. :D
The process for double knitting takes some getting used to, but broken down, it's basically two layers of stockinette with the wrong sides facing each other — so you do a knit in the current side's main colour, then a purl in the contrasting colour, and that's effectively one stitch!