I've designed a case for my cubieboard. Top case is for Cubieboard, bottom one for SATA HDD (you can use USB->SATA adapter from A-Data CH93 or SATA connector from Cubieboard).

Bottom parts needs to be printed with support (45* recommended).
HDD Case can be used separately. You should glue some soft material inside for HDD safety. It is designed to fit AData CH-93 electronics (for USB) or SATA cable.
 
This two cases can be placed on top of each other and connected with long screws or parts of 3mm filament.
 
Power button is part of 3mm filament, melted on one side.

Version v2:

• borders thickness reduced to 4mm.
• bottom of case reduced by 2mm (in version V1 I couldn't connect external ports for GPIO)
• printing time reduced to 60% by modifications above :)
• bigger holes for HDMI, USB-OTG, audio and IR
• HDD case adjusted to Cubieboard case.