Measuring an internal thread

[f350ca]

Needed to make a 55 x 2 mm nut for a hay rake. How do you measure an internal thread? The shaft wasn't available so I had to make a test shaft that I used the 3 wire method to measure then cut the internal thread using the test plug to check the PD. Is there a beter or easier method? In this case he needed the part, none available in north america and an unknown delivery time from Germany.