Raspberry Pi B+ Acrylic Enclosure is a good plastic box for Raspberry Pi, which can protect it with one of these snazzy plastic enclosures. These cases protect the Raspberry Pi from things like rogue wires that might short it out while still allowing full access to the board. Simply snap the Raspberry Pi into the bottom half of the enclosure, then snap the two sides together.
Raspberry Pi B+ Acrylic Enclosure provides slots to access the peripheral header, USB ports, Ethernet, SD card, HMDI, composite video, audio, CSI and JTAG connectors as well as feet and vents to ensure the board gets proper cooling and plus-shaped wall mounting slots. All of the status LEDs on the Pi are visible through the case thanks to light pipes embedded in the design.
Robotshop Web Site: http://www.robotshop.com/en/raspberry-pi-b-plus-acrylic-enclosure.html