PCB edge connectors are a cheap and easy way to connect USB devices to a host by using the PCB itself as a USB-A plug. It looks like this:
You really want the PCB to be thick enough so that it lodges tightly into the USB-A socket. A thickness of 2mm is recommended. My manufacturer quoted a surcharge of $40 for 10 PCBs to lay out my design on a 2mm board. An USB-B socket costs 30 cents.
The USB prototype board will not sport a PCB edge connector.