This design is intended for early prototyping, but could easily be used in a competition robot.  It is simply a mount for: 

• Rev Control Hub
• Rev Expansion Hub
• Rev power switch
• Matrix/Modern Robotics brick style battery or goBILDA nested battery

Mounting holes are included on two sides and follow the goBILDA hole spacing for plenty of mounting options.  Pass-through holes are included to allow for communication and power wiring to go between the two hubs while keeping it neat.  The two hubs mount together using M3 screws and nuts.  I did forget to include a way to retain the battery, but a rubber band does just fine.  There may be an update later to add slots for a Velcro strap. 

STEP for is included for easy remixing.

Print with the largest side down.  You might be able to print without supports, but you'll probably get some stray filament lines where it bridges across for the power switch mount.  It'll still be functional, but won't be as pretty on the underside where the switch mounts.  Painting supports in that area will prevent that if it matters to you.