I have done a bit of searching and not seen anything like these - thinking the kbdfans 5 degree case which has this (unsightly) hold on the bottom - might even damage the pcb if something poked in there. So, I was thinking that someone, somewhere might already have designed a "plug" to blank this hole out. Then, I started thinking about the USB socket, one misplaced cord yank and your PCB would be toast, so would some sort of rubber stopper not work in there as well, allowing the cable connector through, but adding a bit of support/safety.
Just thinking out loud really.
