I was a little disappointed how short the list of tubes was in the ultrasonic tube measurement project. Tbh, that told me people lost interest. You have to get the speed of sound right, but I'm not sure how much it varies among frame steel. The cheap thickness measuring devices won't do it, you need something that knows it might see paint and look for multiple returns because tubing is thin.

I would like to be able to measure new tubes, but not enough to set up my ultrasonic system.