You can find them here. These are the coolest things. You can get one where the pieces can be assembled in different ways or one that is already assembled. I love to turn this treehouse into a seasonal event. At Christmas fill it with pine, in spring moss...
Then go here to get these fabulous wooden animals. 
You can add fairy dolls. This leaves so much to the imagination. One of my favorites. My daughter and I collect the wooden pieces, I try and add a piece every year.
There are 5 different German manufacturers of these and you can find them in handmade shops across the country.
