I have quit using MDF for spoilboards. Plywood will work, but you have to get good plywood. Its hard to find sometimes. The cheap imported stuff wrinkles like a potato chip.
One option is use something other than wood, HDPE plastic, 1/4" aluminum plate, etc. Those get heavy if you have to put the table on and off by yourself. An advantage is they are not subject to moisture.
HDPE is really easy to machine with the bot, and Aluminum works nice too. But its pricy!
I have looked at optical breadboards for base boards on my powersticks, but not spent the money (yet). They are drilled and tapped on a 1x1 grid at 1/4x20 which is just what I want. Clearly a product of someone elses CNC machine!
My old BT-32 has the 1/2" aluminum table base which is a nice solid foundation for the upper layers.
Hope that helps-
"The best thing about building something new is either you succeed or learn something. Its a win-win situation."