We started with TranspOtter at the end of 2017, when we were looking for a way to transport our stuff. Because we already played with (defective) hoverboard parts at this time and Niklas wrote his own firmware the choice fell on hoverboard parts. These parts can be bought used/defective online, while the important part, the motor, is never broken. The Mainboards with onboard ESC and batteries can be bought fairly cheap from AliExpress.
The basic idea back then was, to have a platform on which drinks and Euro crates can fit, which will follow you and works also in harsher environments and higher loads. The base is made from wood with two hoverboard motors and two rolls, for mounting the motors, the original hoverboard frame was used.
To archive the following part, we used something what is called a "GameTrak", these are argumented reality controllers used for the PlayStation 2. In a GameTrak there are two mechanics with one string each, the length and the angle of the string to the GameTrak can be measured. By removing the mechanic and screwing it to the base.
Also see these Twitter posts and build logs for more details: