If you’ve been looking for a robot chassis that can accommodate a wide range of computing and sensor hardware, then look no further than the TurtleBot. As explained here, while this TurtleBot3 can be purchased in both a “Burger” or "Waffle” configuration, it’s entirely possible for you to build this open source device yourself.
The robot is constructed mechanically with a series of interlocking plates, and features space in the lower section for — the correspondingly — lower-level components like motor drivers, an Arduino board, and the driving motors themselves. On top sits the single-board computer (SBC) that controls the overall unit using the Robot Operating System (ROS), along with an optional LIDAR sensor. Notably, this SBC can be a Raspberry Pi, but it will also work with the more powerful Jetson Nano, or perhaps you might select something different like a Latte Panda board.
The DIY TurtleBot travels around via a simple differential steering configuration, and uses encoders with an optional 9-DOF IMU to keep things on track. While the write-up presents a usable setup, it’s meant to be customized to your needs, with many components listed as optional. Whether you buy one or build your own, it’s likely that few if any of those in operation will work the same!