There are a ton of Raspberry Pi cases already, but I needed a simple mounting option for a robotics project. This model just has the minimum that I can epoxy onto any other carrier, and screw down to the board. It has two hollow standoffs that match the two mounting holes on Second Revision Model B (and Model A) boards, and has two other standoffs that should not interfere with underside components.
Print the Berry Simple Pi Tray. Attach the tray to a cabinet wall or other project surface, by clipping, nailing, gluing or whatever means.
I was thinking of including specific nail holes or extra pegs on the outside edge, but any such extras would be particular to the project at hand. This is a starting point for making minimal mount options for the Raspberry Pi. Deriving a new mount from this model should be easy in any STL editor.