Looking for wood shavings and clay for future build

I am looking to scrounge building materials for a future build on my property in western Montana. I would like to build a cabin that can be converted to a sauna or greenhouse later on.  I am looking for clay and wood shavings for the installation similar to the sauna near Cooper Cabin.  Where does one find this stuff. I am a novice when it come to building stuff so if there is other building materials I need please let me know

For wood shaving, look locally for a woodworking shop or a furniture maker.

If that doesn't work for you try the local feed store as they usually carry wood shaving for chicken bedding.

For the clay look at your land.  It is quite possible that your land might have some.

A chainsaw and some log rounds can make an impressive pile of long shavings if you make lots of cuts with the grain. This is the material i used to do the infill on my sleepout project (soon to be documented, just a little too busy right now).