This is actually my second go at making a Griffonstone mode, the original can be found here.
The tree is made from epoxy putty over an armature, the rocks are resin cast from a store brought mold. The houses are mostly made from card stock and coffee stirrers, and the straw is PLA from a 3D pen.
In case anyone is interested, here are some behind the scense pictures of how I made it.