Ideas for a school project with electronic circuits?

Hello everyone,

At school, we currently have a project in NWT where we have to build and design a circuit with a housing, etc. As an example, our teacher gave us an organ for which you can then make a housing and keys using a 3D printer, as well as a circuit to control the keys. As another example, he gave us a circuit that detects when the soil in a plant pot is too dry and then waters the plant using a motor.
We have all kinds of electronic components at our disposal, a 3D printer, CNC milling machines, Arduinos and all the things we want to buy.

Do you perhaps have some ideas what could be done?