A miniature cooling device includes numerous improvements capable of increasing the reliability and useful lifetime of the device, as well as improving electrical power to cooling power conversion efficiency. The improvements include a unitary DC motor shaft design that incorporates a unitary mass flywheel into the shaft element and provides a solid shaft cross-section for increasing magnetic flux density in the DC motor. Additional improvements include a bend resistant flexible vane in the DC motor to compression piston drive coupler, reduced dead space volume within the compression cylinder, improved heat dissipation by a cylinder head cover and an athermalized compressor design that provides uniformly efficient operation over a wide range of operating temperatures. Further improvements include fabrication and coating improvements that increase the life of compression piston and compression cylinder wear surfaces.