Embodiments of a sample testing system of the present invention generally include two internally threaded caps; an externally threaded outer tube having a tapered internal bore and external circumferential grooves proximate each end thereof; an O-ring seated in each groove; and a plurality of inner tube sections cooperatively arranged to form an externally tapered inner tube structure that is disposed within the outer tube; wherein each cap is sealingly attached to an end of the outer tube via threading engagement therewith. Various embodiments utilize at least one closed-ended cap and/or at least one cap having a port extending through an end thereof, which may also incorporate a piston cavity and a piston having two circumferentially disposed O-rings. Embodiments allow for inner tube structure removal and separation of the inner tube sections for cured sample recovery. Embodiments of a method of using the system to cure a sample are also provided.