Here is a goal: How would a person decide how big to make the leather piece for their knife sheath?

How would you accomplish this goal?

Possible answers:
(I). Measure the length of the shaft of the knife then cut the piece of leather twice as long so that it can be folded in half and sewn on the sides to sheathe the knife.;
(II). Measure the length of the handle of the knife then cut the piece of leather twice as long so that it can be folded in half and sewn on the sides to sheathe the knife.;
(I).