Here’s a nice tutorial on making gabions and wattle fences.
Modeling
Making A Model Wooden Cart
The Lazy Forger has a tutorial on making a model wooden cart.
Modeling An Iroquois Longhouse
This photo tutorial offers great instruction on modeling an Iroquois style Indian longhouse.
Sculpting An Urban Wall
A nice tutorial on sculpting and then making a mold of an urban wall.
Basing Trees
Here’s a photo tutorial on basing tree armatures.