We use this testbed to extend the ruuvi tag device. The ruuvi will be placed in the round area and fits to it. small copper wires connect the free I/O pins of the ruuvi tag to a header line, where the extension can be connected.
Images of an experiment can be provided later.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/99baFj4C47p