This is the most simple USB switch I could come up with. It doesn't require IC's or any other complex circuitry.
All it requires is:
One 4pdt switch
Two USB female ports
one USB cable
and a case
Step 1: Prepare the Case
this will differ depending on what you use, I used an old power brick.
Just make a hole for your toggle switch and USB ports
Step 2: Wire the Switch
Now the switch needs to be wired.
It doesn't really matter what order the wires are in, as long as they line up on the switch.
Step 3: Test!
Make sure double check the wiring before testing!
It's a good Idea to test this before you put in the case, otherwise you might get all put together, plug in, and it doesn't work
Step 4: Assembly
Now put your USB switch in it's case and your done