Since I want the project to be as modular and reusable as possible, I built some encasing for each component and custom wiring to plug everything together.
At first I bought a distribution box large enough to fit the relay inside and at least 4 power outlets on top.
Currently I only mounted two power outlets and had to do some adaptations to be able to switch each socket individually.
A Lego case (in red) for the Raspberry was obvious. For more flexibility I made an extension cord for the GPIO Pins with enough room to plug in the relay, the temperature sensor and the LCD Display (also in a Lego case). The power supply for the Raspberry proofed to be sufficient to also power the relay.
Next thing on the agenda, will be the modeling of the state machine to run the LCD Display.