This was a fun project; would have been very quick if I hadn’t been crazy stressed and traveling the whole time I was working on it.
I used standing triple crochets instead of chain 3s throughout and I didn’t slip stitch up the sides at the end of each joining row. I used a contrasting color for the join and the edging so I didn’t want it to look thicker in parts.

Approximate yarn usage:
118 grams / 480 yards = squares and half squares
10 grams / 41 yards = joining
7 grams / 29 yards = edging