Introduction: Moai From Recycled Foam

I've been saving Styrofoam (actually Expanded Polystyrene foam) blocks that came with flat-pack shelves, and I got to thinking that if I had enough of these blocks I could make the Easter Island Head (Moai) that I've always wanted. I called around and found some foam construction blocks that had been returned to the supplier. Since they were rejects, I got these 5-inch, by 7-inch by 60-inch EPS foam blocks for just a few dollars each. Twelve of these blocks (3 rows of four) make a single block 20-inches, by 21-inches, by five-feet tall. [To keep the peace, I have agreed that five feet is a reasonable height for a Moai.]

I struggled to decide what kind of glue to use to make these dozen blocks into a single block. Since they no longer sell some adhesives here, I decided that plain old wood glue (PVA glue) would be the easiest choice. I glued three rows of four blocks together, then glued each of the three big blocks together to make one big block. I tried not to overdo the glue. I just want the blocks to be held together securely. Too much glue will result in undried pockets of glue that will leak out while you’re carving. Many of my glued joints were solid, with just a thin layer of glue between the foam blocks. Many of my seams were not so tight, even having a slight gap, with the glue spanning between the blocks, like honeycomb. This wasn’t really a problem, spackle will fix most any gaps.


Expanded Polystyrene foam (EPS) blocks.

Hacksaw Blade (mounted on a handle)

Bowsaw Blade

Microplane Grater

Woodworking Rasps

Utility Knife

Sanding Pads

Vinyl Spackling Paste

Paints and Brushes

Small Nylon Spatula

Marking Pen

Large Square

3-M Super 77 Aerosol Glue

Wood Glue (PVA)

Step 1: Make the Pattern

Deciding what to make is easy, just choose something that interests you. Drawing the pattern for your "megalith" can be a challenge. I'm no artist, but I know how to trace an image onto a sheet of graph paper (a window helps). And it's fairly easy to transfer an image from graph paper to a full-size grid drawn on a block.

For the Easter Island Moai, I looked at lots of pictures to get an idea of the Moai shape I wanted. I traced a photo onto graph paper, mostly to get the right proportions, then started modifying the shape to fit my block. You need to draw both front and side views, so one way or the other you'll be "creating" your own drawing. To transfer a profile picture to front view, plot your (block) images side-by-side, and use a ruler to project the features from your traced profile (eyes, nose, mouth, and chin) to the front-view, and fill in the details as best you can. Just center the features and fill them in (in pencil) by referring to pictures. I just kept drawing and erasing features untill I arrived at an image that I felt represented the Moai I was looking for.

Once you've got your pattern (front and side views) you're ready to transfer the pattern, square-for-square, from the graph paper to your block.

Note, you don't need to keep your drawing inside your working space (the size of your block, as outlined on graph paper). For features that stick out, but only in a small area, just glue blocks to the larger block, in the appropriate positions. Also note, you can use parts you cut away from the large block to add onto your block.

Step 2: Glue the Blocks Together

The main block is composed of a dozen blocks, glued together. I first glued six pairs of blocks, long sides together. These six, double blocks are then glued together, again along the long sides, to make three rows of four blocks. Each row is 7-inches wide by 20-inches long, by 60-inches tall.

I spread the wood glue with a rubber roller, applying the same amount to each side, and then loosely clamping the parts together, or just weighting them down with my rock collection (take that, people who said I have too many rocks).

It's worth the effort to get the edges aligned properly, so the stacks of four blocks can be fitted together without gaps. I did a light sanding on the sides of the stacks of blocks to allow the seams to press together more closely.

for this project I had to buy more than one pint of glue. It costs about the same for a gallon of glue as it does to buy two pints. I try not to add too much glue because I like to keep the weight down. If you're thinking that this is the wrong type of glue for gluing foam, you may be right. Chemical bonds are stronger (think solvent-based glues), but strength isn't an issue for this figure, and I thought the fused material might be difficult to cut through, and leave harder seams to deal with later. Internet sources advise against using PVA glue to glue flat pieces of foam together because the outside edges cure, but the inside stays wet. I did hit a few pockets of wet glue while I was carving, but it wasn't a big problem. .

The final picture is the completed block with all twelve slabs stuck together (20-inches, by 21-inches, by 60-inches).

I'm going to add blocks of foam to this big block, so I'm finally getting rid of all my scrounged chunks of foam to make the nose, lips, chin, ears, and shoulders.

Step 3: Transferring the Pattern From the Graph Paper to Block

I transferred my sketch of the Moai profile from the quarter-inch graph paper to a grid drawn at a scale of 2-inch squares on the foam block. The grid is drawn on both side faces of the foam block, and the image is transferred to the block square by square (it's harder than it looks). There is no reason to draw a grid on the front face, as most of the front face will be removed when I cut out the profile.

Drawing the image on both sides of the block helps keep the saw blade outside the lines while cutting out the profile. Once you have the rough profile, draw a center-line down the front, the other features are drawn by measuring from this centerline. It seems a little daunting to hack into this big block of foam, but this stuff is pretty forgiving, and there is always spackle. I want it to look nice, but aiming for perfection interferes with the creative process and just stresses you out. It's not like you're entering a contest or anything... oh, wait. Never mind.

Step 4: Add Blocks and Rough Out the Basic Shape

EPS foam is fun and easy to work with. I looked in my tool box (and the kitchen drawers) and grabbed anything that looked like it would help with shaping the foam. I also bought a couple of "rasp-like" tools for getting into hollow places.

I bought a 24-inch bowsaw blade that I mounted in a small handle to make the first, wide cuts. Start the cuts at the top, applying little pressure and only cutting on the pull-stroke (or the blade will buckle). It helps to switch sides every few inches; working the piece from each side helps keep the cut on track. Once the basic profile has been cut, draw a centerline along the cut, and plot the locations of the features. Use the utility knife and a hacksaw blade to work the features down, going a little bit at a time. I ended up having to add more blocks to fill out the features.

For the shoulders, I re-used the part that was cut from the forehead and nose. I also used the big arc-shaped piece that was cut out behind his neck to add rounding to the back of his head.

I took a lot of time trying to get the nose and lips right. Mostly I just took off a little at a time, and tried to keep the features symmetrical. It was really helpful to keep looking at pictures to get a feel for the curves as you shape the foam. You can use the glue-seams as reference points to help keep features the same on each side. I ended up doing most of the carving with a long-bladed utility knife, the kind with the snap-off blades. I also found the short, arc-shaped "rasp" to be about the most useful item for overall shaping. The microplane grater was nice for surface smoothing, but it bent pretty quickly (I doubt if anyone will notice).

If you make mistakes, you can either glue on blocks to fill in large areas, or build areas up with spackle. The closer you can get to the final shape, the less spackle you will need, and the lighter your megalith will be.

Step 5: Work Down to the Final Shape

With all the supplemental blocks glued in place, it's time to work the foam down to the final shape. This doesn't take long, and most of the work can be done with a long-blade utility knife and a curved grater. It's easy to get intimidated about carving into a big block, but this stuff is pretty forgiving, so relax and have some fun with it.

My approach is to go slowly, and not work one area down too far until the other areas get caught up. It's a lot easier to remove material than add material, so try not to take off too much at once. It was helpful to work in stages, stopping to look at lots of pictures before proceeding. If you're not sure whether you sould take off more in a particular area, work on a different feature for a while, it really does help to see how other parts are taking shape, as you work on any particular area. I left the nose, lips, chin, and ears for the last removing a little material at a time, and trying to keep them symmetrical.

Working the foam down doesn't take long, but I took it slowly and worked on it over several days. Don't try to do the shaping in a windy area or you'll make a bigger mess than you'll want to clean up. I kept a shop-vac handy and took breaks to vacuum up the chaff every few minutes. Keep track of where your vacuum cleaner is blowing out air. I've accidentally blown fountains of foam shards into the air.

The final shaping of the nose, lips, chin and ears really makes the figure take shape. The sides still have a grid with some reference markings that I kept until I had all the other features finished. Then I just rasped down the sides, giving them a nice concave shape and meeting the curve of the jaw-line.

I didn't like the flat areas on the ears or the sharp corners at the inside of the shoulders, so I added some more blocks. One of the beauties of working with foam is that you can change your mind and add material at just about any stage of the process.

A quick smoothing of any last touch up areas, and a once over with a sanding pad and "Louie" is ready to get spackled.

Step 6: Trim the Seams and Brush on Spackle

As you're grating and sanding the Moai to shape, the glue seams stick up like a feather. This feather-edge needs to be trimmed down below the surface and filled with spackle to give the impression that it was carved from a solid block of stone.

This joint trimming and filling takes some effort but it makes a big difference in the finished Moai. A small, pointy pair of scissors works well for removing the ridges of glue (If I had a steadier hand I'd probably use the Dremel tool). Hold the scissors flat against the seam, press the tips down below the surface of the foam, and snip. I trim all the seams, whether they need it or not. After the initial trimming, feel the edge with a finger, and snip off anything that sticks up.

It seems like you're doing a lot of damage to your nice smooth Moai, gouging out all the seams, but it's a lot easier filling a groove with spackle than trying to cover over something that's sticking up. After trimming, smear all the seams with a bead of vinyl spackle. Once the spackle is dry give the seams a quick sanding to even up the surface. Be as neat as you can when filling the seams. It's difficult to sand areas that are partly covered with spackle and partly bare. You wind up removing more foam from the unspackled areas, which just makes the bump more noticable. It may take a couple of rounds of spackling to fill the seams so they are unnoticable.

The vinyl spackling paste is water-based and can be thinned to whatever consistency you need. Mix up a thin slurry and brush it over the entire surface of the Moai. The first coat will fill most of the little plucking holes (where balls of foam have been pulled out). When this coat is dry, mix up another batch of slurry, a little thicker than the first coat, and brush it over the entire surface again. This should be sufficient to cover any foam texture and fill in any remaining plucking holes. I only bought one container of the vinyl spackling paste, and I wish I had bought more, as the back didn't get much coverage. Sorry I didn't get photos of spackling the seams, but do you really need to see more pictures of white foam. Once the spackle skin is dry, everything gets a light sanding.

The last step in preparation for painting is to paint on a layer of black gesso. This helps cover brush strokes and any remaining foam texture, but it also protects any areas that didn't get full coverage with the spackle from being degraded by the spray paint used in the next step.

Step 7: Paint and Seal

The fully prepped Moai gets a base coat of spray primer (gray), and then it's ready for the acrylic paint color coat. I sprayed two cans of gray paint on this, but didn't get very good coverage. For the acrylic paints, I just mixed black and white paint in various shades, starting with a darkish gray blotchy coat, overlain by a lighter gray set of blotches, then fine stipple of black and another stipple of white. Finally, I mixed up a thin "wash" of nutral gray and dabbed it all over to tone down areas with too much white, and to ligheten areas with too much black. There is no real rule that I know of, but this seemed to work. I haven't put on the sealing clear coat yet because I may add some patches of moss here and there when my green paint arrives.

There are a few things I learned while doing the painting. The natural sponge makes all the difference, try to find a natural sponge with an even distribution of "fingers" sticking out. Wet the sponge first and dab it in the paint, then wipe against the side of the container or dab it on a pallet (or hidden area of the work) to get the thick gobs of paint off. Try to dab with the same pressure on every tap against the surface, and change the position of your sponge frequently, so you don't develop a pattern. Tap the sponge straight down and lift straight up, to avoid smears. If you make a mistake, don't wipe it off, just paint over it later. For stippling, just give the surface a very light tap, so only the tips of the sponge-fingers touch the surface, and try to tap the same way every time.

I'm trying to imitate the crystalline structure of natural rock, like granite. If you want a different texture you can use the sponge differently, smearing it around a bit on the surface to get a softer texture. The "wash" I used on the last coat was made from acrylic paint thinned with water, with a little isopropyl alcohol added to make it less viscous. It's partly transparent, so some of the black and white "minerals" still show through.

The finished yard Moai stands five-feet tall and weighs about fifteen pounds.

Step 8: Drawing

In case anyone's interested, I took a closeup of my original drawing. Sorry, it's hard to see the graph lines, but they are 1/4-inch squares. Note, I didn't follow the drawing exactly. The mouth is a little different, and I think the nose came out wider.

Recycled Speed Challenge

First Prize in the
Recycled Speed Challenge