Yes, that is a great program he made himself to measure snakes. But if you prefer, get a long string and a helper. Then put the end of the string on the head and hold it with one hand. Then use your other hand to move the string down the backbone until you come to the first bend. At that point, hold the string in place at the bend and use your hand that was holding the head to work your way down to the next bend, alternating hands until you get to the end. Or - use your helper to make it easier with more hands. Sounds complicated, but very easy. Once you get to the tail end, mark the string so you can measure it.
Occasionally you will find your snake stretched out along the long side of its cage, sometimes even going around the corner and stretching along the short side. It is easy to estimate the snake's length once you measure the sides of the cage.