The structure of the main parts within the chamber is illustrated in Figure (detailed description in the documentation repository, see Data and Code Availability statement). The humidity of the chamber is controlled via an Arduino-driven stand-alone software (shared in the code repository, see Data and Code Availability statement). The sample holder temperature is controlled with a resistive heater -thermocouple pair. The chosen LED lamp is stable enough to be used with a fixed operation voltage during aging tests with durations from days to few weeks. In addition to the controls, the chamber includes a separate high accuracy air temperature and humidity logger as well as a feature for detecting possible lamp failures or lamp aging retrospectively from the image data (described in the documentation repository). The building block design presented above facilitates implementing only the necessary parts of the chamber when the design is adapted for future applications.