Last weekend I cut a hole in the side cover of the moped to place the speaker.

The speaker is a water resistant Visaton FR 8WP-4SW for use in boats, cars etc.

The PCB is already fully populated (pictures will follow). Next week I will finish the first version of the project. The only challenge is to put the PCB safely inside the moped so it doesn't get wet. And build a kind of case to put it inside.