I've used an old briefcase to make a portable Raspberry trainer, to teach me Python and try to teach my kid some Scratch.
I've fitted 48 18650 cells to power all, it's a little heavy but it last a lot of time, and also due I want to use a portable 24 iron solder. There are three power supplies, one buck-boost from the battery to 24V and two little ones to supply 5V to the LCD and the Raspberry. Also a battery monitor to know how much remains and the temperature.
The raspberry hdmi is connected to a portable monitor of 13 inches, it's an IPS screen and has a very good illumination, also it powers from a USB C with 5V 3A
I've used an USB SSD to put all the roms for the Retropie, and it works perfectly.
The iron solder is a SQ-001, that works with 24V ad heats up very fast.
The raspberry GPIO connector is wired to a little protoboard that will help to connect some devices.
A keyboard also is stored under the lid, were the batteries and power supplies are.