Young programmer Luke Spademan has built up a CamJam EduKit 3: Robotics kit and, after first of all using the excellent worksheets written by Tim Richardson, then converted it so that the Raspberry Pi inside the box can be controlled by a pair of micro:bits. You can read how he did it here and see the code on GitLab here.

I reckon there’s a way to control the Raspberry Pi over Bluetooth from the micro:bit, so I’ve asked Luke about it and will look further into it as I think this is an excellent control method using the accelerometer chip on the micro:bit to control direction.

Edit: Indeed, there is a way to control the Pi over Bluetooth. Barry Byford sent over this link which you could add to Luke’s work to just use a single micro:bit.