Hollow core, bifold doors for closets found at the Home Depot are light and very sturdy. You (or if power tool challenged) or a neighbor can cut it to length and dress up the edge.
MDF. Heavy but sturdy, stable and machines nicely for a decorative edge if you like. In my mind, the heavier the better if for no other reason than stability.
This is a big enough model that I think warrants a durable, substantial base.
Good luck with the build.
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"
