Methods and systems for building arbitrary motor controllers are described. An example motor controller may include multiple motor power boards connected in a stacked configuration and coupled in parallel. Each motor power board may include one or more power transistors and one or more gate drivers having an input terminal coupled to a control signal connector and an output terminal coupled to a gate terminal of the one or more power transistors. The example motor controller may also include a power bus connector coupled, in parallel, to a respective output terminal of each of the multiple motor power boards. Further, the example motor controller may include a control system coupled to the control signal connector and configured to selectively enable a set that includes one or more of the multiple motor power boards based on an output power requirement.