ACME Anvil Prop From Recycled Styrofoam




Introduction: ACME Anvil Prop From Recycled Styrofoam

I hate having to throw away big chunks of styrofoam, and I've been saving some blocks that arrived as packaging. I have been reminded that they can be recycled, but I have insisted that, someday, I'll make something out of them.

As it happens, I have always wanted an anvil and I have been trying to make a convincing argument for getting one. "I just want one" is not a convincing argument. Not only are anvils noisy (when in use) and difficult to move, but a good anvil is both hard to find and extremely expensive (not to mention shipping!). Finally, it occurred to me that I didn't really need a working anvil; instead, why not make a model of an anvil -- using my prescious blocks of styrofam.

Making one of the heaviest objects immaginable out of one of the lightest materials imaginable, what could be more fun! Styrofoam is easy to shape, using a hacksaw blade, grater, and sand paper. You just sketch the outline on the foam blocks and cut a little outside the lines. The grater brings the surface down to the final shape, and a couple of layers of spackle hides the popcorn texture and fills in any holes and seams. Getting the overall shape of the anvil is absurdly simple, and surprisingly fast. The key is learning how to apply a convincing paint job.

I had most of the blocks I needed for this project on hand, but for the body of the anvil I bought one large styrofoam block, measuring 17-inches long, by 11-inches tall, by 7-inches wide.


Styrofoam Blocks

Hacksaw Blade With an End-Handle

Carpenter's Saw

Utility Knife

Drill (or just drill bits, you can drill styrofoam with your fingers)

Microplane Grater

Sand Paper

PVA Glue

Dowel, 1/4-Inch Diameter, about 18-inches long.

Vacuum Cleaner

Vinyl Spackling Paste

Acrylic Paints and Brushes [Note: most spray-on paints will melt styrofoam.]

Black Gesso

Rusty Metal Spray Primer

Burnt Umber

Burnt Sienna

Terra Cotta

Cadmium Yellow

Metallic (silver)

Fine-Point Scissors


Nylon Spatula

Exacto Knife

Step 1: Make the Pattern

For the pattern, I found a picture of an anvil that I liked, and traced the outline onto graph paper (with quarter-inch squares). Then I transferred this shape onto a big sheet of graph paper with one-inch-squares. The finished pattern is cut out and laid on top of the styrofoam blocks to draw the outline.

The anvil is still in blocks, so I made the horn piece separately, and will attach it later. The photo shows the horn, with it's roughed out shape. It's just taped in place for this picture to get an idea of the proportions.

Step 2: Cutting the Blocks

I'm using several blocks to piece the anvil together, and it's easier to shape the rough outlines of the blocks separately. Later, after I glue the blocks together, I'll go over the final shape with the grater and sand paper to blend the parts together and make sure the glue seams don't show.

To cut the styrofoam blocks, I'm using a (worn out) hacksaw blade, attached to a handle that came with a small hand saw. I found that it's best to lay the block flat, while cutting the shape, being careful to keep the blade vertical while making the cuts. It's easiest to make the profile cuts (front and back) first, then stand the piece up and make the curved side cuts (as viewed from the top).

The excess material on the "horn" is roughed out with a utility knife, and finished with the microplane grater to get a nice round shape of the horn. Just shape it by eye, we're not making a piano.

Working with styrofoam is super easy, but really messy. You don't want to do this outdoors on a windy day. I found that I could do some of the shaping with the work piece inside a large plastic bag. This contains most of the chaff, but you will also want to have a vacuum cleaner handy to pick up the chaff before it blows around. If you're using a shop vac, be sure you have the hose hooked to the vacuum side, not the blower side. I wasn't paying attention and ended up with a big cleanup.

The last cuts are the flat, side cuts to narrow down the upper part of the anvil. This big block is too long for the hacksaw blade, so I used a regular carpenter's saw to cut off the upper part of the sides. Just be careful not to make the cuts too deep, or you'll have to glue the feet back on. Don't worry if you make small mistakes, the entire surface is going to be covered with spackle, and it's easy to fill in gouges, though you may need to apply the spackle in stages, for large repairs.

Step 3: Gluing the Parts Together

The horn overlaps the joint between the body of the anvil and the top block, and you can either glue the top block in place first, or add it later. Be sure to keep the top block in mind when mounting the horn, so it doesn't come out too low.

I bought this "special" foam glue, but it wasn't very impressive. It looks and smells like regular PVA glue (Elmers), perhaps a bit thicker.

I also think the glue works better if you don't (or only gently) clamp the styrofoam blocks together. Clamping pushes out most of the glue, and I ended up having to re-glue several parts, where it seemed like there was too little glue to hold the pieces together. Next time I may try using 3-M Super 77 aerosol glue. It dissolves the styrofoam a little, but creates a chemical bond that holds much better than PVA glue.

Even though this is just for display, I wanted the horn to be attached more securely than just with glue, so I cut three pegs (about five-inches long) from quarter-inch diameter dowel, and drilled holes for mounting the pegs in the parts that will be mated together. The dowels are glued in the holes with regular white (PVA) glue.

To get the holes to line up, I drilled the holes in the horn first and set short pegs in these holes. Setting the horn in position, and pressing the short pegs into the body of the anvil leaves marks for where to drill matching holes. Then you just replace the short pegs with long pegs, and glue them into the horn. Once the glue is dry, apply glue to the pegs and to the flat parts that will be mated together. Press the parts together, and hold them in place gently, wiping up any excess glue that leaks out of the seam.

The anvil needed a bit more material added to the feet, so I cut four blocks from a piece that I cut off of the large block. The four rough blocks are glued where the feet go and will be shaped later. The clamps are not tight, they are just to hold the feet in position. I had some fabric tape left over from another project, so I added strips of this fabric on the underside of the seams to make the feet more secure.

Step 4: Final Shaping and Prep for Paint

With all the pieces glued together, it's time for one last round of shaping with the microplane grater and a light sanding to remove some of the shreddy bits. Shaping the Styrofoam is really easy, it just takes a good eye, and a little restraint.

When you sand a glued seam, you're left with a ridge of glue sticking up. Use some fine-point scissors to go over the seams, pressing the scissors flat against (and a little way into) the styrofoam. You want to cut off any burrs that stick up above the surface. Everything will be covered/filled with spackle, so don't worry about cutting too deep. After trimming the glue, the seams get another quick sanding (to make sure there are no bulges), before spackling.

For the first coat of spackle, make a thin mix of vinyl spackle and water, and brush it over the entire surface. This will fill in most of the "plucking holes" (where balls of styrofoam pulled out). After drying and sanding, a second coat of spackle slurry covers any of the remaining styrofoam texture and fills any imperfections. Larger dings may need a couple of layers of spackle.

At this point, I was going to add some dents and dings to make it look authentic, but I couldn't bring myself to beat it up. Styrofoam is pretty soft, and I figure it will get dinged up enough just playing with it.

Step 5: Make It Look Real

Before spraying on the base coat of primer, I brushed the entire surface with a layer of black gesso to cover any places where I sanded through the spackle. The colors will be applied in mottled layers to try and achieve a naturally rusted anvil look.

I found Raymond Potter's wonderful instructable on painting rust effects, for model builders, and I mostly followed his tutorial: , and another painting tutorial (from another website) by Colleen Jorgenson: In addition, I accidentally discovered that you can give the surface a "rusty texture" by spraying a second coat of primer (from a distance) when it's hot outside. The paint globules partially dry before landing on the surface, leaving a sandy texture. This texture made it a little difficult to smear around the next coats of paint, but it wasn't too much trouble, and it did give a nice rusty look.

An anvil deserves a name, and in honor of my life-long inspiration, Wile E. Coyote, it had to be the good old ACME Brand (appologies for any copyright infringements). For the lettering, I just found a font that I liked, and blew it up to 150 size. I used some old fashioned carbon paper (do they even make that stuff anymore?) to trace the lettering onto the anvil, and then carved the letters into the styrofoam with an exacto knife. After a couple of coats of dark paint the lettering looks pretty convincing.

As per Colleen's instructions, the,"rusty metal" spray primer makes a good base coat. The other colors were dabbed on, followed by some dry-brushing of silver metallic paint (followed by a little bit of black-wash) on the strking surfaces. Raymond's instructable describes (in the comments) how to make a wash using acrylic paint, water, and a few drops of isopropyl alcohol. Finally, the whole anvil gets an even coat of clear, matte finish spray paint, to protect the rust!

I can't wait to surprise my friends by asking them to help me move my anvil. You do have to be a little careful playing with it, as the styrofoam dents fairly easily.

The fial anvil is 34-inches long, and 12 1/2-inches tall, top surface is 4 1/2-inches wide, and the base is 10-inches wide, by 16-inches long. It weights under 2-pounds.

Now I just need to find a big round from an oak tree for a stand to make the gag complete.

Bonus points for those who noticed that I left out the hardy and pritchel holes. I thought the holes would weaken the prop, so I left them out. Hmmm, maybe some black paint...

Note: Since all the styrofoam is covered with vinyl spackle and gesso, solvents in the spray paint won't damage the foam. Most aerosol paint will dissolve styrofoam, so you shouldn't use spray paint on bare styrofoam. If you use solvent-based glues, make sure you test them on scraps before using.

Step 6: Bonus Step - Blacksmith's Hammer

I figured I needed to make a foam hammer to go with the styrofoam anvil. This chunk of foam is different from the styrofoam used to build the anvil. It's very springy, similar to the polyethylene foam padding they use for cushioning stuff. I though this would be better for something like a hammer, but for various reasons it didn't work as well as I had hoped. Next time I would use a utility knife instead of the grater, which didn't produce very crisp corners.

For the handle I just used a piece of 3/4-inch Schedule 40 PVC Pipe. I drilled into the end of the PVC pipe with a stepped drill bit, to cut out as much of the flat cut on the end as possible. This leaves a fairly sharp edge on the end of the PVC, and by making a few angled cuts in the thinned edge of the PVC, you get saw teeth (after a fashion) that you can use to drill the PVC pipe neatly into the foam hammer head. I cut the PVC handle a foot long, and it goes most of the way through the hammer head. The PVC is wrapped with a piece of 1/4-inch thick adhesive-backed foam, glued along the long edges.

The end of the PVC pipe is plugged with a wooden ball that I whittled to fit inside the pipe. I used the E-6000 glue to mount the hammer head on the handle, and regretted it the next day. I had tested this glue on a small piece of foam, and it didn't seem to react. But after several hours, the glue on the handle had degraded the foam to the point where all the sides were concave. I filled the depressions with spackle and repainted the hammer, but I don't really care for this repair job. I did learn something about testing material reactions; you need to use a realisitic quantity and wait to see the results.

The hammer head build follows the same process as for the anvil: brush on a thin spackle slurry, sand and cover with a second (and possibly a third), heavier, coat of spackle. This vinyl spackling is really easy to work with, you just add water to get the consistency you want. I have a little nylon spatula that came in very handy for shaping the hammer head.

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    Reply 2 years ago

    Thanks. I hope to see more posts about things people make out of styrofoam. It's kind of a blast to work with.


    2 years ago

    Very nice and VERY convincing.
    I think most anvils have mounting holes on the base to bolt them down (like gravity was not enough). So if you want to add yet another convincing feature you could add mounting holes. Thanks for sharing this great Instructable.


    Reply 2 years ago

    I appreciate the kind comment. This was actually a lot of fun to put together. I'll think about adding mounting holes.

    Treasure Tabby
    Treasure Tabby

    2 years ago

    Now you can be the coyote from Loony toons. ;D


    Reply 2 years ago

    That's my plan. Only this time, the roadrunner gets cooked.


    2 years ago

    That's fantastic Ive always wanted a foam anvil, You could have some fun putting it in weird places, On top of the fridge, on the roof rack of your car, in a shopping cart, on the toilet, on the cat, on your neighbors driveway....


    Reply 2 years ago

    Thanks for the comment and the great suggestions. So far all I've come up with is asking someone to help me move it. I imagine it would draw some odd looks if I put it on my roof rack. At just over a pound, I could even wear it as a hat, though I can't think what occasion would call for something like that.