My latest project has been a two-sided hat. I tried double knitting, but it was too difficult for my untrained fingers, and I went with the old siamese twin hat trick. Cast on with a provisional cast-on, knit one hat, then picked up the cast-on edge and knit another hat.
The first (blue) hat was too small, and the second (gray) hat was smaller, even though the yarn seemed to be the same size it came together tighter. When I put them together, it only really works well if the blue is on the outside, otherwise it bunches up inside the gray.
So what with the added thickness of the double layer, the finished hat is too small for almost any adult. Fortunately, I live in China and among my students there are some very petite people, one of whom will probably be receiving this hat. At least I have learned a few new tricks, and have now two very precise “gauge swatches” for these similar but different yarns.