[JChavis]

To me it looks like a frame that would be optimized for four (4) mecanum wheels, where that opening would be the side you draw in game pieces going sideways. Maybe the shooter or shooting mecanism would be for both directions. Long explanation short, I think that you have taken a picture of the "right" side of your robot, with the "left" on the other side.....however, I do note that the wheel slots might not be big enough. But then again, this could only be the shooter component that might be bolted onto your robot drive base....