Mounting bracket for 23b's Open Access Control System, board version 2.11 (see http://code.google.com/p/open-access-control/ )

Depending on the kerf of your laser, you may need to adjust the size of the board and wire holes. They're set at 0.1" which was alright for #4-40 screws on my machine but could be a bit too loose on yours. Likewise, the wall holes are set to 0.3" and 0.15" for drywall screws, your mileage may vary.
Any length screw can theoretically be used, you just need to make sure you account for the space taken up by the Arduino beneath the OAC board. I recommend 3/4" for the board and 1/4" for the optional wire management holes.
Eventually I'd like to see this be a complete laser cut enclosure.