This is a housing for the spark fun xbee carrier (the one with a mini usb connector) and an xbee module (one with an external antenna).
There is a version with and without a hook to hang it from your laptop screen (it's sized for a macbook pro but should fit many others as well)
Print it out.
There are holes that are intended to be used to secure the board into the case. It's an ok friction fit but you can put some short 3mm screws in the holes or maybe just some short little stubs of 3mm filament to keep it in the case.
The lid for the end is held on by the antenna connector.