I was wondering the same, but I thought the number of illustrations would be 7!/2 = 2520, that is, the number of permutations for 7 different elements, divided by 2 because symmetrical sequences generate the same drawing.

Is it incorrect? How do you get "6!" ?

720 custom doodles seems doable, 2520 seems a bit much, so I suspect my reasoning for 7!/2 is wrong :)

Edit : oh, I see how for all closed paths all 7 permutations are the same so we can divide by 7 for closed paths, but there are still the open paths... hmmm (still pondering)

Edit 2 : aaaah, got it, I did not notice he was always closing the path himself... tss that's cheating :)