Non-wooden enclosure for Model100

I live in Finland, and during winter time, stuff made out of wood tends to shrink (and then in the summer, expand again). This is a problem with the Model100 wooden enclosure. My left shift key got stuck in the pressed position, because the surrounding wood pressed on it. I sandpapered the key cap to be tiny bit smaller to get it to work again. When the winter is over, and I can actually take off the wooden enclosure, I plan on filing the opening around the key caps to be larger to avoid this happening again, but for now the enclosure is very tightly stuck to the plastic plate underneath the keys and PCB.

I had similar problems with the Model01.

Are there any enclosures made for the Model100 that aren’t made of wood, or that made of wood that doesn’t move with the seasons? Possibly plywood?