Rubber Mallet Mjolnir




Introduction: Rubber Mallet Mjolnir

About: Cosplayer/amateur seamstress. Slightly befuddled at all times.

And lo, from the bards of Marvel came a tale so stunning, so touching, so blockbusting, that throughout all the land, the people were shaken. And yea, the cosplayers did come-

Look, the point is that I made a Thor costume for San Diego Comic-Con, and I needed Mjolnir to go with me.

You can find several tutorials on this site for replicas of Mjolnir, but I needed something in between cardboard and metal. I had a couple criteria for my hammer: it needed to be light enough to carry around all day at a con, it needed to be small enough to fit into my suitcase, it needed to be sturdy enough not to be crushed mid-flight, and I needed to be unable to injure someone with it.

So here, for your entertainment, is what I came up with: a foam hammer built around a rubber mallet. Turned out pretty slick, in my oh-so-humble opinion.

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Step 1: Supplies!

Here is everything you will need:

For the base

- 1 16oz or lighter rubber mallet. These run about 5 USD at Home Depot.
- 6 blocks of dry floral foam, 8x4x3 in. Floral foam comes in three varieties: wet and two kinds of dry. You want the softer kind of dry. You should be able to nick it with your fingernail (but don't).
- several sheets of thin foam, similar to these. Whichever ones you use, they need to be at least ten inches on one side and about seven on the other.
- 1/2 to 3/4 yard of very thin, stretchy fabric. I used leftover bathing suit liner from a Question costume from long ago, which was ideal. You'll be working from the selvage in, so the width (45", 60", etc) of the fabric is immaterial (ha!).

For painting

- gesso. I used most of a 16oz bottle.
- foam carving utensils. I used a regular-old butter knife and a spoon.
- a variety of paintbrushes. You'll want a bunch of foam ones for glue, at least one big one for the gesso, and some for the paint.
- a 2" foam paint roller
- a variety of acrylic paints. You'll want gold and silver metallics for sure, along with flat grey and white, but if you find one color that's exact, go with it.
- palettes for the paint
- a small bottle of brush-on matte acrylic sealant

For the handle

- strips of leather or leather-like vinyl, enough to wrap around the handle. Remnant leather is just fine.


- a pair of sharp scissors. Foam sheets do not like dull.
- a few disposable plastic cups (Solo cups)
- a frankly ridiculous amount of Tacky Glue or similar substance. There are glues made for floral foam, but Tacky Glue didn't have any problem holding.
- a ruler. I strongly urge you to invest in a Dritz See-Thru Dressmaker's Ruler or similar product. Changed my crafting life.
- a pen or mechanical pencil
- some straight pins, preferably the ones with the flat heads. You will not be getting most of these back, so don't use Mamaw's that she used to sew your baby clothes.
- a drop cloth or a LOT of newspaper

This looks like a whole lot of supplies, to be sure, but a lot of this stuff is stuff that you probably already have at the house. The biggest expense was the gesso, which ran me about 16USD for 16 oz, and I had almost all the paint already from other projects. Minus the gesso, this piece cost me about 40USD.

Step 2: Basic Construction

Basically, the theory here is that we're going to use the mallet as a base and build from it. This gives the hammer a little heft and prevents us from having to risk the handle sliding right out.

First, measure the mallet's head. Take two pieces of foam and put them on either side of the hammer; 4" side goes parallel to the handle, 3" side goes perpendicular to the handle, 8" side goes parallel to the head. This is your basic shape.

Let me give you this advice before we move on: Foam. Gets. Everywhere. You will end up with foam dust and foam pieces all over you and your floor. If you do not use a drop cloth or put down newspaper, you will severely regret it.

Using these pieces, carve out a shell on either side for the mallet. This is easier if you score the foam before you start scooping it out. This, clearly, is not precision work, but no one will see it, and if it stays it plays.

For the area around the handle, do not carve all the way down. Carve only enough to go allow the handle to pass through. Try to make the hole as tight as you can left-to-right as well. Note here in these pictures that only one side is cut close, because I did the first one before I figured out what I was doing. When these are carved out, put the mallet inside and glue the pieces together. You don't need to worry about putting the handle straight up and pressing the sides together. The mallet makes this all very stable from all sides, so you can lay it on its side to dry.

Take two more blocks of foam and put them lengthwise at the ends. You don't have to bother with whittling them down like I did, as that idea got nixed. You can also just use one block of foam cut lengthwise. Glue them on.

At this point, I cut the sides down, because the whole thing was just too long. I left about an inch of the extra foam on on both sides, making sure to measure from the handle and not the ends.

Step 3: Foam Coating, Part One

Step two turned out to be mostly optional, but it helped anyway and it illustrates what we'll be doing next, so I'll detail it here.

Paint and gesso will not take on floral foam, so we need something that will hold paint and smooth the floral foam out. Craft foam works perfectly for this application.

So cut craft foam to fit and glue it onto the floral foam, remembering to put the glue on the craft foam side. Press together, let dry. You don't technically have to do this right now, but it made things easier later.

At this point, I put on a layer of gesso, thinking this was how the thing was going to look. It looked like a shoebox on a stick, so we moved on to step three.

Step 4: Foam Coating, Part Two

So the problem we face after step one is that our hammer looks like a shoebox. We did NOT come all this way to make a shoebox, my friends.

The solution I came to was to add another inch on the top and bottom and carve it off. You will only have two floral foam blocks left. Take a block and carve out 1" pieces on both sides- DO NOT cut a 1" piece and then cut another one from the side you just cut. Go over to the side where you haven't cut and cut a new one, so that you have two flat sides. Do this with both blocks.

Put the foam blocks on the top, right over the shell blocks. You could glue them down at this point, but because I already had that craft foam, I just pinned them in, making sure to stick the pin way down in. You'll need to cut another piece of foam to cover the last bit; pin that in and level it off with the other two, planing it until there's a smooth surface. It does not have to be level, just good enough for the craft foam to go over it. Repeat all this on the bottom, making sure to cut notches for the handle.

Now we can make this hammer look a little more hammer-shaped. Carve off the edges to give it a hammer-y shape. I eyeballed this one, and it looks fine, so don't worry too much.

That done, do the same thing we did before: cover up the floral foam with craft foam. The slanted edges won't want to stay, but you can pin them down- sticking the pin in only a little, not up to the head- and then pull the pins out later.

Don't worry about the edges of all these foam pieces meeting up, because they're just not going to unless you're some kind of foam-whisperer. We'll take care of that in the next step.

Step 5: Fabric and Gesso

This is where the fabric comes in. Here, we'll make a nice little fabric wrapping for the box, which will even out all those corners.

The basic idea is to take the fabric and wrap the box up like a present. Make sure to keep your fabric under even tension. This is why you should have flat-headed pins. Learn from my fail. At some point I just decided that if they'd have had rivets in Asgard, they'd have used them, so I just pinned stuff down. Using glue is an option for a smoother finish, but I've really got no idea how that would work.

Now, at this point, having whittled down the fabric on my ends and pinned it in, I got something that looked like the third picture. That is enormously jacked up, my friend. I tried to gesso over it to smooth it out, but there was no way. At this point, I put pieces of foam on either end and tacked it down at the corners. Trust me, this is MUCH better than the alternative, which was to gesso straight over the ends, as in the fifth picture.

Awful, right?

Now it's time for the gesso. This is where the red Solo cups come in; I used them to hold the gesso while painting, since mine came in a bottle. Gesso's not hard to work with at all, though you will only be able to paint a certain number of sides at a time. Every coat takes 24 hours to dry, and you will need several coats. Fabric is thirsty, so don't be afraid to make your coats thick. Be careful as you brush, because your fabric is under tension, and remember to push a little into the cracks and crevices where the brush doesn't reach. Don't forget that you need to rest this on something; leave one side unpainted so you can rest the hammer on something flat. The gesso can and will glue your hammer to your drop cloth/newspaper.

At some point while you're doing this, take a piece of foam and give it a few coats of gesso while you're painting. You'll use this to test colors in the next step.

Now go and do something else for a while, checking back once a day to repaint. Right now, your hammer should be bright white and rather innocuous.

Little do they know.

Step 6: Painting

Now that we have our big white hammer, we can focus on turning it into a big gray hammer.

There are a number of paints you could use, but I chose to go with acrylics. They're very forgiving, getting exactly the right shade is comparatively easy, and they're cheap.

If you find precisely the right shade straight from a bottle, I salute you, but if that doesn't happen, you'll need to mix your own shade. Take your paints and mix them in very small amounts (a few drops at a time) until you have what you want. Don't just slap something on; go slowly and make test swatches of everything you try. If you run out of gessoed space to make swatches on, you can paint over more foam with white acrylic paint, which will give you a rough idea.

Once you know about the ratio of the paints you want to mix, take another solo cup and mix up a big batch of it. It is definitely better to have too much; if you run out mid-paint job, you're going to have to start over, unless you can very precisely match the paint color you've created. If you have leftover paint, you can put saran wrap over the cup to keep the paint from drying out.

Now you're ready to paint. Make sure to lay down several even, thin coats instead of thick ones. You can use any kind of paintbrush that makes you happy, but I used a little foam paint roller, which gave me a nice coverage and minimized my brushstrokes. There will be tons of little places where white will show through, so make sure to go through and patch them up.

Here's where an optional step begins that I'll talk about later; if you want to add embellishments, cut them out of paper and glue them on when the next to last coat of paint is dry, and then paint right over them.

While you're painting, paint all the way down to the end of the handle. Also remember to cut out a small foam circle and paint that separately, remembering to paint the sides. When the final coat of paint is dry, glue the circle to the top of the hammer.

When I was finished, my hammer was- well, it was really really gray, and not so much metallic. The way I fixed this was with a metallic wash. An acrylic wash is really easy; just mix paint and water, about three drops (or more, depending on the effect you want) of paint to about five tablespoons of water, and apply it the same way you'd apply paint. But be careful: unlike acrylic paint, this will drip pretty easily, and if you don't catch it quickly enough, it will leave streaks. Just go slowly and watch yourself. It also doesn't dry evenly, leaving you with darker areas, but for this application, that's a feature and not a bug, as far as I'm concerned. You can see the crappy flash picture above to see how it's shiny now, rather than flat.

Now, slap on a coat of sealant (which will also drip, be careful), and there we have it! If you're adding embellishments, go on to step seven; if it looks good, go on to step eight.

Step 7: Optional: Embellishments

So the problem with our big gray hammer is that it's kind of... boring. Thor's hammer shouldn't be boring.

There are three major embellishments that Thor's hammer has at different times. In general usage, there is scroll/braidwork around the slanted sides; while magic is being magicked, a trefoil appears on one side; sometimes, the words ("Whosoever holds this hammer", etc) appear on the other.

You can do what you like. I have shaky hands, so the braidwork was right out, and I've yet to see someone do the words and make it not look silly (I'm including the comics), so for me, the trefoil it is.

I messed with this thing forever, and I can't even really tell you how I did it, because I'm not sure. Here are some tips:

- It looked cooler when I did it outside the sealant, because it separated it from the rest of the hammer.
- A trefoil is three-dimensional, not flat. Trace your way through it and see where it has to cross itself. Mark these passes out when you do your outline.
- I outlined this in gold and then did a gold metallic wash to fill in the lines. When it was not quite dry, I ran a dry brush over it to make it a little worn-looking.
- At some point you will just have to let go and let God on this one. As soon as it starts to infuriate you, put it down, do something else, and come back later. You may find that it looks cooler than you thought.

Once that's good and dry, we can move on to the handle.

Step 8: Handle Wrapping

We are in the home stretch! All that remains for us to do is to wrap the handle.

There are loads and loads of different ways to wrap a handle in leather. I opted for the simplest way possible; a really complex leather wrapping job would have looked sort of out of place with the almost cartoon-ish design for the rest of the hammer.

All I did, which I unfortunately don't have pictures of, was cut some thin brown leather into two strips, about 13/4" across. I pinned them to the underside of the hammer and glued them in a spiral down the hammer, one after the other. This gives a lattice-work pattern with big diamonds showing the handle- which is why we painted the handle in the first place.

I trimmed them off at the end of the handle, making sure to glue them in well. Then, with the remnants, I glued a loop of leather to the end- remember, it's not really Mjolnir if it doesn't have a loop to swing it by (DO NOT DO THIS, IT WILL COME APART)- and then wrapped another piece around the loop to secure it and hide the ends.

And now, brave traveler, we have reached the end.

Step 9: Final Thoughts


You need to block off at least four to five days to do this project. However, almost all of that is waiting for things to dry. Without waiting for glue, gesso, and paint, it took maybe six hours to complete, and it could easily be done faster.

This was my first real attempt at prop making, and I'm sure there is a lot of room for improvement. The main thing I would change is the bottom; this is definitely a "no don't look at it from there" prop. The one of my objectives I didn't hit was making it harmless- you could do some damage with this thing, though probably not without denting the hammer itself, so please look out.

Overall, though, I'm very pleased with how it turned out. I think it's worthy of being carried by Asgard's greatest warrior, at least when he's played by me.

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