A robust plastic third sound resonator has been developed which permits a wide range of experiments to be carried out on superfluid helium films. At room temperature the cell can be filled by diffusion with a wide range of gases including He, Ne, Ar, N2, and CO2to form both substrate and experiment. The highly flexible walls allowinsitupressure measurements with a resolution of 10−6Torr. Third sound can also be detected with capacitor plates within this cell.