Some more pictures for your viewing pleasure.
Figure 6. Score Board side panel removed.
Figure 6 shows the left hand side panel removed. You can see the Arduino Mega mounted to the rear of the sliding panel and the 2 I2C wires and 2 power wires coming in to the first Rainbowduino. On the left you can see the cable coming from the rear. The reason there is an additional white wire is that the actual wiring I used contains 5 wires, and I totally forgot about 5v that I needed to send to the ping pong table. My bad 
I will hopefully clean this up later. The green tape holing the two cables together does look very fancy though, so I might leave it.
Figure 7. Score Board Side panel.
Figure 7 is a picture of the side panel that has been removed in figure 6. It is made of aluminum as is the rest of the box. Flush mount rivets and captive nuts make it extremely easy to remove and install.
Figure 8. Score Board right hand side.
Figure 8 is a picture of the right hand side of the score board. Nothing really special to describe here. I could comment on the frosted glass table that was purchased from Freedom Furniture 3 years ago, but I wont ;D
Figure 9. The Arduino mounted to the rear of the slide panel.
Figure 9 is the underside of the internal sliding panel. The Arduino has been mounted to allow the slide rail to move without any interference. The fit is extremely tight and keeps the score board housing looking really clean. The green sticky tape is an essential part of the mounting hardware 
All the wiring is just stripped wire that has been soldered and shoved into the pin sockets. This is due to making the fit so tight that there is not really room for a more suitable solution. It works at the moment so I'm happy.
Figure 10. My table simulation setup.
Figure 10 is my beautiful Ping Pong table simulator. The 4 buttons represent the players buttons on the actual table.
If you would like any more pictures, please ask. I am happy to take custom shots.
Dan.