Here is a picture of my main control panel. This one runs two loops with relays to operate two trains per loop. The control to the left is for the turntable via crank and clothes dryer belt. The panel is 1/8 inch Masonite with Radio Shack mini switches, both push button and slide. Track outline is auto pin striping. The 1/8 Masonite fits in a groove at the top and has three small screws on bottom edge to allow the panel to be easily remove and tilted up. The wires have 12 inches of so slack to allow swinging up for maintenance of or adding switches without having to work under the control panel. My layout used to be on the floor.
Smaller control panel operates a third loop and one more train for total of 5. I use 3 LWs for the the three loops and various 12 v trans for lights and a 14 v trans for 27 Marx switches. All three loops can be controlled via the LW on the left. There are various stages of using the the 3 LWs from one, two or all three. The TV is for X-10 homemade color camera car.
I see you are now doing your control panel after building the layout. I sure am glad I wired the control panels as I built the layout, just to keep up with all the wires.
Charlie
Main control panel for two loops and turntable
Smaller control panel for third loop . Trans to right for HO trolley