Throwable Mjolnir

This project makes a great last-minute touch to make your Thor costume really come to life with a fun trick to make any party more exciting. You can actually throw it and (if you are worthy) it will come back to your hand.

If you enjoy this build please vote for it in the Halloween contest between Nov 8 2021 and Nov 10 2021.

Check out the Build video here. Link to build video It gives further instruction on some harder to describe parts.

Or if you just want to see Mjolnir in action check out the short film we made here. Link to short film

Materials

2in 5"x9.5" Pink insulation foam (Need 2)

1in 5"x9.5" Pink insulation foam

16.5in 3/4 PVC Pipe

Heavy Duty Key Reel (Rated for around 8oz)

3d Printer for handle end cap

Leather Belt

Cardboard and spray paint for armor

Cut a piece of 3/4in(~7/8in Outside diameter) PVC pipe 16.5in long

Now cut a notch in one end that is 2/3 in wide by 1 7/8in deep. (As seen in the Mjolnir Build Manual PDF)

You may need to file the notch so that the key reel fits smoothly inside. A secure fit will be important when you are throwing the hammer.

Now make a mark 4in away from the end opposite of the one you notched. Wrap a leather belt between this mark and the bottom of the notch. Cut the belt at these end points so that it completely covers the pipe to the line perpendicular to the length of pipe.

Glue this belt onto the pipe and secure the ends with strong rubber bands. I used construction adhesive to do this. A friend will be handy with this part. Be careful not to get glue or tape on the belt surface as this may destroy the finish depending on your belt type.

Cut 2 5"x9.5" rectangles from a piece of 2" foam. I used a radial arm saw to keep the edges straight.

Cut 1 5"x9.5" rectangles from a piece of 1" foam.

Glue these with the 1" piece in the middle as seen in the picture above (Drying time may vary depending on the glue you use. I used construction adhesive and left it to dry over night.)

After dry you are now ready to draw a line 1/2inch in from each side on the short side. Then draw a line 1inch from the edge on all long sides. These will help us cut the chamfer. Use a serrated knife to make these cuts. Also a friend is handy to spot the other line to ensue you don't cut too deep. If you are confused on how to do this reference the build video.

We now want to cut a 7/8in diameter hole in the center of the long edge with the foam edges visible(Refer to picture above for where this hole for the handle needs to go). I use a long straight hot knife or other sharp knife to make this cut.

After all cuts are made, use an orbital sander to smooth the cut surfaces. This is also an opportunity to smooth any lines that may not have lined up perfectly. Make sure to keep the sander flat to the surface. You don't want to round the edges just smooth the surface. (wear a dust mask or respirator and do in well ventilated area).

Now clean up the dust and we are ready to add the details.

Print off the Hammer Details print (In the Mjolnir Build Manual PDF attached in the supplies section).

Now is a good time to sketch the straight detail lines on the bottom half of the hammer. (Dimensions also in PDF)

Separate the emblem from the page and use it to trace the lines onto the surface of the foam.

Now use a hot knife with point tip to etch the lines into the foam. Vary speed to vary line thickness

With this done it is time to paint.

I chose to use metallic spray paint because it will have a better finish and shine.

But many spray paints will dissolve foam.

To prevent this, brush a similar metallic acrylic paint on first. Should do 2 coats.

After acrylic is dry use spray paint to finish. Just as you do with any spray paint, pass quickly over the surface to prevent concentration of paint in one spot. This will reduce runs and the chances of dissolving all your hard work.

Now is also a good time to paint the 3E printed handle cap. Now is a good time to note that at this time I know very little about 3D printing. I made the file and a friend, who is a master of his craft, 3D printed it for me.

After the metallic paint has dried use a black acrylic paint mixed with water to brush in the details of the hammer head and handle cap. Do this as you see fit. The slight black outlines will make the details pop.

Now take you key reel and cut off the clip on the back side.( See picture above for location of cut).

Drill out the holes in the key reel.(pointed out in the picture above).

Now insert the key reel in the slot in the PVC. Secure it by putting wire through the two holes you just drilled in the key reel and the holes in the PVC. You can add some hot glue to this but I would not trust only hot glue.

After reel is secured hot glue the handle cap halves onto the handle end. Make sure they do not obstruct the use of the cable from the key reel.

Now take the 4 inches of exposed pipe and hot glue into the hole of the hammer head. Make sure the glue is not so hot it melts the foam but hot enough to get the handle all the way in.

You are now done with the hammer. Find a secure way to strap the cable to your wrist and have fun.

Look at the picture for how I made my arm sleeves for attaching the cable to. What we made for this is actually kind of complex and hard to work with. You may be better just using string or a Velcro strap.

Take a large piece of cardboard 39" by 30" and cut as shown by the base plate cuts in build manual.

After the base plate is cut to shape you should roll the parts that will go around your body. This will help it fit better later. But make sure not to bend up the front surface where the details will attach. You will also want to roll the belt pieces later when you get them cut out.

Now print off the armor stencil in the build manual and use pumpkin carving tracing tool(pictured above) to transfer the lines to cardboard. Then go back and trace the indented line with a marker

On the edges that under-lap a higher layer you should leave a tab so that the higher layer has something to overlap. This will give your armor more depth when glued together. If your confused on this part refer to the build video linked at the top of the page.

Once you have everything cut it is time to spray paint. We used the same black for all the back layers and the same metallic paint used for the hammer. The shine was pretty impressive but if I did it again I would consider covering the cardboard surface with acrylic paint first to give the spray paint a more smooth solid surface that does not absorb the paint so much. Also if you will use hot glue to secure the details to the base plate make sure to use tape to cover the areas that will be glued on top of. Hot glue does not stick to spray paint.

When the paint is dry punch holes in the base plate as seen in the build manual and string up as seen in the picture above.

Now you can attach the armor details to the base plate using hot glue. See the build video for the order.

Cut a piece of red fabric that is ~42" by ~66"(Depending on height) for the cape.

We wrapped the to corners of the cape around the base plate shoulders and used safety pins to secure it. Glue another safety pin to the the back side the the silver spiky details above the shoulders so that it can be pined to cape to hold them back. You could also just glue all this in place if you don't mind gluing the cape.

Finally for the boots print off the stencil in the build manual to assist in drawing the lines on the boots then paint with a gloss silver metallic acrylic paint.

Now you get the enjoy your work and amaze your friends with your new party trick.

It will take some practice to throw the hammer and successfully catch it again (do this before breaking something at the party). I find it easier to learn by starting to throw it more vertical then as you get better try to get more parallel to the ground with your throws.

Again if you enjoy this build please vote for it in the Halloween contest between Nov 8 2021 and Nov 10 2021.
Also please check out the short film we made with this outfit. Link to short film

After some use the cable pulled out of the crimp inside the key reel. Because the reel is not really designed for this use case it is likely yours will do the same. I was able to fix mine by taking the cable out. threading it through backwards then knotting the end in the plastic end. It is not terribly difficult just hard to explain. Please refer to the build video for more information on how to do this fix.

If you want little to no chance of it failing you may be interested in the lighter build I did. Same concept but not as detailed so it is about half the weight and a little smaller in size. See at this link.