Making this square as part of my new Groovyghan for the Campervan.
My first go using a 5mm hook per the pattern was I felt, too loose and floppy. I reduced the hook size and made the following changes:

1. Ch 5. I found the 4ch just too tight to fit 12sc.
2. I started each round of dc with 2ch, hooked quite loose (counts as first dc). The 3ch was too loopy.
3. When I got to the outer rounds, I did 2 of each in the ch2 gaps. The pattern says 3, but I found this made my edges ruffle.
4. Last two rounds were simple sc, with sc, ch1, sc in each corner. These changes made my square the same size as the others I’ll be using for my Groovyghan and a much more solid structure..