Measuring circumference on odd shaped, asymmetrical toys can pose a challenge, but after many years of practice here’s how Scott does it. The blue tape is there for demonstration purposes, as in practice you would just use your finger. Just make a knot somewhere near the end, wrap it around the point you want to measure (here it’s maximum circumference) and pinch the string and hold it where it meets the knot. Then hold the string over a measuring tape or ruler with the knot at zero, the measurement where you’re pinching the string will be the circumference.
The string method is great because it’s not always obvious where the largest point is, so this way the string can go around the top and then be worked down the toy until the maximum wrap is attained, much in the same way as your hole would stretch around the toy in use. Be sure to use string that does not stretch.
Using a flat tape directly on the toy will most always give you an inaccurate result due to the flat shape of the tape compared to the curved toy surface. I’ve illustrated this below by getting 2 false measurements using a flat tape measure along with an accurate one as confirmed by the string method. The difference between the 3 is only .2 inches circumference, or about 1/16″ in diameter, which is is why it can be a challenge to get an accurate measurement with a tape. If one doesn’t know of this variance that can occur with using a flat tape, one might get a false measurement and believe it to be the true one without retrying. With a string, there’s virtually no risk of that.