Maybe build one with a short piece of large diameter PVC pipe as the coil form. Use a signal generator at 60 kHz to drive a smaller, transmit probe coil. Then

Maybe build one with a short piece of large diameter PVC pipe as the coil form. Use a signal generator at 60 kHz to drive a smaller, transmit probe coil. Then another receive probe coil hooked to an oscilloscope. Use this loose magnetic coupling technique to tune the large coil for resonance. You'll of course want to shoot for as high of Q as possible, but that's an engineering trade off of AC wire resistance, capacitor Q, etc. Go for as large of inductance as feasible, until your self resonance is just above 60 kHz, then pull it to down on frequency with a silver mica cap, or adjustable air variable cap.