I forgot to respond to your comment about how the hexagons are joined. Contrary to what I thought before I started, the hexagons aren't knit separately then joined. As you cast on for a hexagon, you pick up stitches along the edge of the hexagon(s) you're joining it to. So by the time you join the round to start knitting in the round, your new hexagon is already joined to the rest of the sock. There is no seaming needed.