I may or may not be following you. Let me ask, where will you get the ultrasound, without an expensive device? Or do you mean something like blowing a dog whistle at something that needs ultrasonics? 'Cause you shouldn't expect that to work. Maybe you can rig some sort of ultrasonic equipment against a flexible, water-filled tank. But I'd doubt that'd be remotely functional, unless almost as expensive as store bought.