Thankfully, OverDose Terrain Studio have come up with a great MDF alternative which is cheap & quick to build!
We purchased a number of the corridor sets from Scorched Earth Store (who make these under license from the Israeli designers) on Etsy to test them out, and final product has to be the most straight forward build and quality product we've seen for a while.
They are all flat packed and who sheets of MDF per set. The instructions don't have pictures, and are really car guidelines rather than actual instructions.
From unpacking to the section being finished took about half an hour and was really easy.
The above pictures only have the wall panels dry-fitted in, and as you can see they are snug - a good sign this has been well designed.
++ Verdict ++
Ideally this weekend we'll be able to give them a coat of Rustoleum (to seal the MDF or the paint just soaks into the wood) and then get some paint on them.
From what we have seen of the rest of the range, the ability of the OverDose Terrain Studios product is super flexible allowing you to add rooms behind doors, or corridors, basically whatever you like!
If you like your dungeon crawler games, or are part of the large Zone Mortalis community amongst the 30K crew, then these are well worth your while.
There may be other sellers in your area, but for us Scorched Earth did the trick nicely.