Cyberdeck
In short: A cyberdeck is a portable, often self-built computer in cyberpunk style.
In more detail: The term comes from the novel “Neuromancer” (William Gibson, 1984), in which hackers dive into the net with a cyberdeck.
In Depth
In the maker scene
Usually a Raspberry Pi or mini PC with a small keyboard, display, battery (rechargeable batteries) and a case from the 3D printer or a suitcase. Often with Wi-Fi, radio modules and tools for network tests (nmap).
Why?
For fun tinkering, as a learning project and as a rugged mobile computer. See microcontroller.
See also: Raspberry Pi, Microcontroller, 3D Printers, Rechargeable Batteries