Not exactly a "living tree" (more like a fallen trunk). I took my first shot at creating a tree this week to disguise an ABS pipe I used as a sleeve to contain a compressed air line and electrical conduit to my shed. I wrapped the pipe with some scrap carpet. Bound it up with tie wire, threw in a few pieces of rebar and wrapped the whole thing with expanded metal lathe. Simply used mortar with a extra shot of masonry plastic cement to build up a scratch coat. Big lesson learned about getting your lathe as tight as possible. The more it flexes when putting on the mortar the more it all just falls off. I just about gave up trying to get anything to stick. After a couple of days got brave enough to start adding carving layers. This picture is before I started to stain it out. Can't wait to work on a true living tree type of structure. Carved with a nail head and screw driver. After first layer of carving, used anchor cement that sets up in about 10-15 minutes to make a paste that would stick once it got to a claylike stage to create multiple layers of bark like you see on pines and redwoods. Just put a ball of "clay" on a existing bark like shape and pressed it out with a margin trowel. Very quickly thereafter it was hard enough to chip off to look like layers of bark.