See saveitforparts' video on making a cyberdeck for some ideas
Portable compute, as-modular-as-possible I/O, easy access to internals on the fly Physical switches, hinges for opening case…
Tough suitcase-like enclosure with asymmetric depths (thinner top for display/compute, larger bottom for keyboard + storage…)
fully 3d printed case
bend some sheetmetal into what we need
Power consumption is a priority because of portable portability constraints.
An ARM device makes the most sense, however for x86 compatibility low-power variants exist such as Intel Atom CPUs.
Needs to be rugged, ideally water resistant
Capacitive touchscreen is preferred