[ILikeRust]

Depends on the stud sensor and how easily you can access your tank from the outside.

I have an ultrasonic stud sensor, which detects changes in density - it sends an ultrasonic signal through the sheetrock, and as you slide it across the wall, when the sound bounces back off of a stud, instead of empty air space, it beeps and lights up.

I could see applying it to the outside of the fuel tank and sliding it up and down until it encounters the fuel. Start at the top of the tank and slide downwards - when it encounters the fuel, it will detect the change in density because the sound waves will bounce back rather than going into the empty space.

Not very practical in my case, being that the fuel tank is under the cockpit and not very easily accessible.

I have made myself a nice black walnut stick, on which I have marked 1/4-tank increments.