Detailed below is a project where you can use an aftermarket EEG-device to control toy robots with simply your brain-waves.
In this example, the Hexbug Robotic Spider was used. In 2014, each one cost 30$. The EEG sensor used was a NeuroSky Mindwave costing 70$ at the time. Additional tools were Arduino and a work computer to connect it to.
The most challenging part of the project is soldering the remote’s buttons to wires which will connect to an Arduino. An additional ground wire is also necessary.
It is recommended that this be done by an adult though the rest of the project can be accomplished by high school students.