The 4' x 8' table top is 5/8 inch thick. I would have used 1/2 inch, but the local supplier did not have it. Might have to use more supports under the table top for a firmer base. Time will tell.
I painted the top to a color that closely resembled the soil of the Sierra Nevada mountains where the NCNG operated. being red/green color blind makes this a challenge. At least it isn't pink or purple.
A friend of mine from high school sent me a box of dirt that is close to the color - I will use this in detailing the layout later.