The band was too large for my wrist.
After printing, and a bit of filing to make the watch pin holes thin enough to fit a pin to my watch, I found that the band was too large. I cut one side almost in half, then used acetone to glue the two pieces together. Remember, this was printed in ABS.
This made one band about half the length of the other band, which was the correct size for my wrist.
Good luck !
Using the following options in Customiser:
strap_width = 24
strap_length = 24
pin_radius = 1.2