If you are using our AstroBox or a pcDuinoV2 (or any other Linux board that only has 1 USB port) you will need to add a USB hub. These run for $5 to $20 at any electronics store. Simply plug the hub into your AstroBox/pcDuinoV2, then plug your camera and your printer into the hub. You are now good to go!
Raspberry Pi: The Raspberry Pi does not have an onboard wifi module (the pcDuinoV2 does have onboard wifi). This means you will have to use up one of your USB ports for your wifi dongle. If you have a RPi B+, you have 4 USB ports, so you're all good. If you have a Pi with only 2 ports, you will need a hub.
Basically, on the Pi you need to plug in: 1) Wifi dongle, 2) Printer, 3) Camera. At the moment we do not support the Pi Cam, only USB cameras. We're looking into supporting the Pi Cam, we just haven't been able to get to it yet.