If you do this as an individual, this could get you anywhere from a misdemeanor to a felony in some states. If you're a cop and do it, it counts as a 4th amendment search.

Neither "make the device" illegal, but they do make using them for the designed purpose illegal. In the same way owning a sawzall is legal, but using one to cut down all flock cameras in your town is illegal. As it stands, they're about $100 on Amazon with several options to choose from.