The bracket that hold the four LEDs used to monitor traffic between the Laptop (4), Raspberry Pi (3) and the Arduino (2) also houses the fan push-button control switch, a rocker switch to shutdown or wakeup the Raspberry and a "Run" LED. The bracket formed from 1" square aluminum tube is mounted on top of the layout.
The monitor bracket houses (on the left) the fan push-button, 2 orange & 2 blue traffic monitoring LEDs, the RPi control switch and the green RPi ON LED. The RPi control switch is a momentary-on rocker switch, sleep in one direction and wakeup in the other with off in the middle. Shaping the ends may need a MIG welding unit.