Some items were shipped to my work in 3/4in. XPS. This is the stuff that you can use to make a fermentation chamber. I have measured out my pieces and there is still a lot left. I think you could measure out a Son of a Fermentation Chamber and double line it to make the wall 1.5in thick.
Here are the plans.
I am wanting to get rid of it in the next few days so please PM me if you are interested.
I'm in Whittier.