I thought (and still think) this puzzle is easy.
But (yes there is always a “but”) i’m getting strange output from my algorithm witch appears logic to me.
here what i did to solve this puzzle:
1- compute the polygon containing all the clues coordiante.
2- i assume than that the circumference of the “ribboned” area should be the circumference of the computed polygon + the length of an arc (of a circle of radius 3: the minimum distance) at each point

the problem is that my program is giving me results far from the expected one.
if you think my logic is wrong please let me know.

Your logic is right. Don’t forget to divide the circumference by 5 and round up as the statement asks for the required number of 5-foot-long rolls. Also observe, if that may help, that the sum of the arc angles (and, by the way, also make sure that you are considering the external angles) satisfies a very simple relation.

Yeh, this puzzle is very easy, and that’s why i was so dumb not computing the distance between the last and first point of the polygon . @Niako thanks a lot for the hint about the arc external angles sum