[poliss]

12mm MDF is what I use and seems to be very sturdy. I built a cabinet with it to house my layout with two shelves for storage underneath. The sections underneath must be at least 2 foot long without bracing and there is no sign of warping after 5 years of use.

 

[poliss]

A nuisance dust mask is no good for cutting any kind of wood. Use a proper respirator mask. Read the safety label for suitable masks.

 

[poliss]

If you use extendable track accross the joins you shouldn't need to have exact right angles. Extendable track also solves the problem of having to raise the hinges for a folding board. Think I read about it on this site.