it's not so much a reprap design, other than the enclosure/battery compartment. perhaps just take a 5 port network switch and hack in a battery pack. Something like a USB hub, but for Ethernet.
Sometimes when doing network troubleshooting, you are just one port short when you want to plug in something temporarily. small switches are fine, but then you also have to carry around the power brick. I can't seem to find ANY battery powered switches.
