The pitch of the conductors within the USB-A shell is 2.5 mm, 2.0 mm and 2.5 mm, so a 4-hole wide piece of perf-board gives almost exactly the right spacing between the 5 v and 0 v pins. Scraping away the two central conductors on the strip-board ensures we don't short anything out.

The space inside the connector's shell is a little thicker than the perf-board itself, so heaping on bigger globs of solder will help fill the gap and make the connection.

I can't guarantee how many amps you can pull. I can't guarantee this won't physically damage your USB-A sockets. I certainly can't guarantee you won't burn down your house with this hack. I can say for certain, though, in a pinch you can get a small fan spinning.