This is a small bracket you can snap a standard Apple-brand USB charger into. Add it to existing enclosures for things you might need to power by USB, like this nightlight I designed for example. Now you have an appliance you can power and attach to the wall in any home in North America (or Japan). Ideas include: a Raspberry Pi Zero, an Arduino, an ESP8266 type chip, pretty much anything that you can run on 5v/1amp. The world's your oyster, etc.
It was hard to find a balance between keeping the plug secure, and not putting too much stress on the PLA when you snap it in. I found the best solution was to keep it a bit looser for durability, but add a notch so that you could use a ny-tie to really secure things if your project demanded it.
I designed this in Blender, using lots of modifiers, so if you wish to modify this general idea to fit whatever USB power supply you prefer it should be pretty easy. Please remix this and feel free to grab the blender sourcefile above. Maybe it's finally time I learned to make parametric things, I don't know. I just love Blender.