This case came from a free box and I put a phone (also free, cracked) in it running termux along with a battery and bluetooth keyboard. I cut a hole for a piece of string to hold the case at a good angle and a hole on the other side for a usb cable to pull power from a portable solar panel to charge the battery. Unfortunately you can't charge the battery and charge/maintain the charge on the phone at the same time but I might make a circuit for that later.

The phone, battery, and keyboard are held down with bicycle inner tube and slices of stick from invasive pineapple guava cut with a hand saw and glued down with a hot glue gun.