Abstract: A floating mounting structure is provided for protectively mounting an electronic circuitry system within an automated external defibrillator case. A method of assembling an electronic circuitry system within an automated external defibrillator case is also provided. A circuit mounting system is utilized and includes a spacer and a shock mount. The spacer may include cut out portions to accommodate raised elements on circuit boards of the electronic circuitry system. The spacer is disposed between two circuit boards which may be affixed to each other. The affixed circuit boards and spacer are folded within the shock mount and disposed within the defibrillator case. Alternatively, a single mounting structure may be used to secure and protect the circuit board within the defibrillator case. A shielding may be present on an exterior surface of the foam mounting structures to protect the electronic circuitry from electromagnetic interference.