Hexagon width through round 6 = 7.5” (between two flat sides), 8” height between two points, and each additional nested strip will add about 6.5” in height. My join method will draw things in a bit, so the final dimensions will be slightly smaller than this (should still be big enough).

I made 72 hexagons and 10 half hexagons (using one of the layouts in the original pattern - see picture/diagram). This should work up to about 73” tall and 52” wide. Finished dimensions after edging are 75” tall (peak to peak) and 54.5” wide.

Note, at the end of each of rounds 1-5, I am omitting the final chain stitch — instead, cut yarn at end of last dc, pull strand through, and do an invisible join to the first dc with a needle (this will essentially create that last chain stitch).

Invisible join video: https://www.youtube.com/watch?time_continue=152&v=bsH...

At the end of the final round (round 6), I did the final chain and slip stitched to the first dc, leaving a long tail for joining (could also keep with the invisible join here, but I didn’t bother). Need to save a yarn tail of at least 3 hexagon lengths to have enough to comfortably join to neighbor piece (I unraveled my sample to figure that out - double check that next time so you don’t waste too much yarn - I was actually saving 4-hexagon lengths, and it was way too much).

UPDATE 8/19/2020: I’m about to start another of these, and I unraveled the final round (round 6), including 3-hexagon lengths of yarn for joining, and measured it. I will need 12 yards for the final round per hexagon. This is helpful for calculating the amount of yarn needed if using the same color for all borders. Be sure to take into account half-hexagons and afghan border.

To join two completed hexagons together, hold pieces with wrong sides together, then slip stitch through both pieces, going through both loops on each piece. This will leave a ridge on the right side, which I think looks great. See picture, and also this short video I made while joining one of these I made in 2024:
https://youtube.com/shorts/6FKwWMUf1OM?feature=share

I joined into strips first, then joined the long strips together.

After joining the whole afghan, here’s how I did the first round of edging:

--> I continued the corners as-is (2 dc in last stitch of last hexagon on the side, chain 1, 2 dc in first stitch of next hexagon).

--> On the half-hexagon/full-hexagon sides:
For the full hexagons, I just did one dc in every dc. When I got to the join between a full and half hexagon, I gathered the two pieces a bit and pushed my hook under both sides of the joining ridge, putting a treble crochet (tc) there. I did this to gather things up by the ridges, given my joining technique. Then, along the side of the half-hexagon, I put two dcs in each dc row, and put three dcs in the center “eye”.

--> On the top and lower edges (the zig-zaggy edges):
On the edges and “peaks”, just continue as you did with the hexagons (on the peaks, 2 dc in last stitch, chain 1, 2 dc in first stitch of next hexagon). When you get to the “valley” between two hexagons, do something like a dc3tog, but do a tc for the middle part instead: in the last dc of the first hex, yo, insert hook into stitch, yo, pull through stitch, yo, pull through 2 loops (like a partial dc) -- 2 loops on hook; yo twice, insert hook into BOTH spaces of the first and second hex (together), yo, pull through spaces, yo/pull through 2 loops twice (like a partial tc) -- 3 loops on hook; yo, insert hook into first dc of next hex, yo, pull through stitch, yo, pull through 2 loops -- 4 loops on hook; yo, pull through all 4 loops. See pictures.

I did one additional round on the edging - all hdc. For the “valleys”, I did sc3tog across those 3 stitches (though, the second time I made this afghan, I tried a hdc-3-tog… not sure if that was an improvement). For the “peaks”, I did 2 hdc in dc before the space, one hdc in the space, and 2 hdc in the first dc after the space.