Design of structural members made of wood–plastic composites (WPCs) is not possible without accurate test data for tension and compression. The viscoelastic behavior of these materials means that these data are required for both the quasi-static stress–strain response, and the long-term creep response. Their relative incompressibility causes inherent difficulties in creating effective clamping devices that do not preload the specimens. In order to conduct repeats of both test modes at multiple stress levels for at least 90 days, uni-axial test apparatuses must be economical and mass producible. Further, all tests must be conducted in an environment that is moisture and temperature controlled, creating space constraints. This paper describes economical apparatuses for both tension and compression creep testing that do not preload the specimens, require a minimum of floor space, and are easy and safe to load and unload. The operation and typical data for the tests are presented to demonstrate the apparatuses.