Sometimes LEGO hackers feel compelled to cast aside the (actually pretty sophisticated) EV3 Intelligent Brick and use some other control system on their robot. They choose microcontrollers such as the Arduino UNO and microcomputers such as the Raspberry Pi and BeagleBone Black to serve as the brains of their project (see Figure 5.1). It turns out there are plenty of cool reasons for swapping out the EV3. In this chapter, I go over some of the major factors in choosing whether to use one of these devices and which one. Finally, I share some cool no-EV3 projects I have encountered.