Love this pattern! It has inspired me to experiment with entrelac. I completed one GG and decided that I did not like the way the seam worked. I wanted to figure out a way to join the two ends invisibly, without the first and last row of base triangles. For this turban, I actually ripped out the first row of base triangles (very fiddlely ripping out from the beginning end -- not recommended) and knitted the two ends together by picking up stitches from the first tier of right leaning rectangles as I knitted the last row of the last tier of left leaning rectangles. Then I went back and sewed the sides of the rectangles together. It made a fairly nice seamless look.

After completed this one, I thought it would be much better to begin without the first tier of base triangles, rather than ripping. So I experimented with a sample and tried a few different ways of starting the first tier of rectangles. Heres the best way I found:

Skip the tier of base triangles.

Start by casting on one stitch. Complete the left edge right slanting triangle as in the directions.

Start the Right slanting rectangles by casting on 6 stitches and follow directions, except you won’t be purling together any stitches. It will also be easier to seam at the end if you slip the first stitch of every row, instead of just the purl rows.

For the right edge triangle, cast on 6 as above, and complete as in directions.

Then knit the rest of the turban until you get to the last tier of left slanting rectangles. There are a few different ways you can handle the join. You can cast off in the last row of each rectangle, and then sew the two ends together. This would be the most straightforward way to do it. If you want to make it more complicated, you can try picking up stitches from the edges of the first tier as you knit the last tier of rectangles. Or you can just knit as in the directions until the last row and knit the last row stitches together with the first row edge stitches, then sew the sides of the rectangles together.