Thanks for comments and fixing the image link. :-D
The board is in Sweden called MDF (Medium density board), 8mm. I wanted to build it as light as possible since you should be able to carry it. 8 mm was almost to thin for the screws, had to drill all the holes before screwing. Then its primed and painted in dark olive green.
The “side boards” are not attached to the big piece and im not sure if they will be.
The map is from a friends “World at War” add-on, scaned and edited in PS. Made some cosmetic fixes, added the “northern passage” over russia (we havent tried it yet) etc.
Left to be figured out is how to cover the “hole” that will be in one end when its folded in half, have to be some kind of lid to protect the map and the plastic sheet covering it. I also want to make a better way to keep track of upgraded and damaged factories!