Kali is a security and penetration testing distribution, preloaded with a wide range of network tools and other utilities. If you'd like to use it on a Raspberry Pi with the PiTFT display, there's only one real problem: It uses a custom kernel which doesn't presently include all the stuff you need to use the PiTFT as a touchscreen. We'll go over the basics of an install and remedy the kernel situation.
One of the more noticeable limitations of the Raspberry Pi is using an SD card for its main storage. This guide details hooking up an external drive, copying your root filesystem to it, and configuring the kernel to treat the external drive as root. It includes a helper script which automates most of these steps.
If you've ever needed to compile the Linux Kernel on a Raspberry Pi, you've probably noticed that it takes a long time. We sure have! If you have a desktop computer or a laptop with decent hardware specs, it seems like there ought to be an easy way to use all that processing power to generate a new kernel for your Pi, but it can be tricky to figure out the specifics. Enter the Adafruit Pi Kernel-o-Matic!