This is a rack for holding phones, tablets, and similar devices for charging. It's designed to have an Anker USB charger popped into it; it will hold the charger in place so that you can readily plug USB cables into it.
I think that's the particular Anker model that this is designed for. Measure yours and adjust dimensions as required.
Full disclosure: in preparation for publication, I improved this a bit. I haven't actually printed the improved version because I don't need another one. It looks OK...
Tip it onto its back for printing; it doesn't require any supports.
Unplug power cable from charger.
Slide the charger in from the back, then across (popping over the ridges) into its final place.
Replace power cable.
(With this improved version, you might not have to remove the cable to put the charger into place.)