I had a lot of fun putting together this Treebeard costume for Halloween this year. It took a weekend to make the head and another day to put the body together. It was a pretty rushed build, I needed to use a heater and hair dryer to dry the paint and clay quickly enough but somehow it all came together. I've put notes on most of the images to explain the steps but some of them only show up if you expand them.

Most of the effort went into the head. It has a base of cardboard, with layers of papier mache, plaster of paris (which is awesome and hardens in about 10 minutes) and a super light weight air-dry clay for the details. I really appreciated the help I got from the folks at the Utrecht art shop in San Francisco, they steered me to just the right materials even though some of them were cheaper than the ones I was looking at and gave me the tip about using the air-drying clay.

A lot of people asked me about the eyes at the party; I made them by printing using a photo printer on some thick photo stock, I was surprised how well that worked. To make them 3D, I cut a spiral slit in them and bent them into a shallow cone. After that, I put some "triple-thick" acrylic varnish on top for a bit of shine.

Being an electronics geek, I couldn't resist throwing some LED fireflies in the beard just for good measure.

Step 1: Materials

Cardboard, lots and lots of cardboard!
Glue gun and about 20 sticks of glue
Basic kids acrylic paints. I used about half a bottle of the the relevant colours.
A big brush, this saved a lot of time.
I started with papier mache with flour and water paste but then switched to...
...plaster of paris, which is both easier, more fun and dries faster
Light-weight air-dry clay for the details. This stuff was great to work with; it sticks well to cardboard, dries quickly and it's really easy to shape.
Gesso, which is a really thick white paint that covers all the different materials to give a uniform base to paint on.
Google, to find pictures of Treebeard to work from.
Wire mesh, to form big features before applying the clay/plaster. Saves a lot of drying time and material.
Box knife, clay tools, scissors.
Absolute minimum of 3 days, even if you use a hair dryer and heater to dry the materials as fast as possible.

Step 2: The Head, Skeleton

I formed a basic cylinder from cardboard, sized it up and added some eyes that I printed on a photo printer. I started with a free eye template that I found online as a GIMP XCF (I can't seem to dig out the link now though).

Then, I formed the nose from some wire mesh that I found at the art shop and hot-glued it in place. Pro tip: hot glue goes through wire mesh, be careful not to burn your fingers.

Step 3: The Head, Building Up the Bulk Features

I started with a simple flour and water- based papier mache for building up the features on the face. It worked OK but it was incredibly slow to dry. I ended up using a hair dryer for about a couple of hours to get it dry.

Plan B: I hadn't worked with plaster of Paris before (so I was a bit wary of starting off with it) but I picked some up at the art shop because it looked cool. Turns out it's really easy to use and it has a great texture for this sort of build. It worked well, hardened in about 10 minutes and dried fairly quickly with the hair dryer (it hardens long before it fully dries out).

After I'd got the face to a good point, I started building up cardboard detail on the back of he head. I didn't have enough time or plaster to detail this to the same level as the face but I don't think that matters.

Step 4: The Head, Painting

The head got three layers of paint and some details:

One layer of gesso, which is a white primer. If I had a do-over, I'd mix in some black paint so that I was starting with a grey base. That way, little nicks in the upper layers wouldn't show up as much.
One layer of reddish-brown.
One layer of greenish-grey, applied with a fairly dry brush. It lets the brown show through in cracks and crevices, which is what we want.
For the details, I added highlights and lowlights using dark and light versions of the above paint. I actually dropped blobs and white and black into my mixing bowl and only partially mixed them. That way, I could pick up a bit of dark or light on each trip to the bowl.

Step 5: The Head, Finishing Touches

Some of the finishing touches I applied:

I glazed the eyes with triple-thick acrylic varnish. That stuff is so thick it forms a shiny bubble over the base that looks like tears. Perfect!
The beard, which is made from Spanish Beard Moss. The stuff comes in a big tangled mess. I found the best way to use it was to look through the clump for a section where all the fibres were running parallel and then to cut that section out while holding it tightly together. Then I glued it on like thatch, pushing it up against its neighbours. Finally, I injected hot glue into the beard by just pushing the nozzle of the glue gun into the beard and pulling the trigger as I pulled it back out again in lots of places. That kept it together pretty well.
Mossy details, made from standard terrarium moss. I just tore it up and hot-glued it on.
Leaves: I bought a string of fake leaves from a nicknack store.
Foam padding inside.
I made some LED fireflies for the beard. I put the code up on my github.

Step 6: The Body

I had to move fast on the body because I was building it on the same day as the party so I couldn't capture as many stages. That said, it's very similar to the head except without the plaster/clay details. I didn't bother with gesso, except for some parts that I'd painted earlier while I was making the head.

I made the arms out of two cylinders glued together. The legs should have been similar but I was running out of time so I made a sortof skirt instead.

I didn't come up with a good way to join arms to the body (velcro wasn't up to the task) so I was holding them on most of the night.

Step 7: Final Thoughts

I had a great time making my costume but it did take longer than I'd expected, especially with drying time involved. Next year I might have to plan a bit further ahead! some things I'd change if I made it again:

I'd make room for my nose in the head, I didn't leave enough room and my nose was squashed all night.
Use plaster of Paris straight away.
Spend more time on the arms and legs.