This Faraday cage is perfectly adequate for a phone. Or just wrap it in Alfoil. Make sure to switch off your phone or put into flight mode as the OS will boost the signal to the max, thinking it's leaving cell. Draining your bat.
When in flight mode, many phones still track you.
When you're a "person of interest" many phones will track and listen even when it is "off" (powered off)
Remember when you take it out of the box, you will ping you immediately.
While we're talking #Opsec, don't take your phone to a demo. Buy one of these pre-internet digital cameras (and don't take pix of demonstrators/blur them)
P.S. A microwave oven will permanently fsck your phone if you need a fast zap.
