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How To Make a Foam Dagger Prop For Your Loki Cosplay

Here's a great tutorial to crafting a simple foam dagger for the God of Mischief.

Foam Dagger Prop
Images Courtesy Winterstar Cosplay

EVA foam is a great material for making cosplay props — it’s cheap, easy to acquire, and easy to work with! Plus, it can be used in so many different ways. In this tutorial, I’m going to be showing you how to create a con-safe dagger prop out of EVA foam.

First off, when creating your prop, you will need some kind of pattern or design to work with. You may want to begin by gathering some reference images, especially if the dagger is for a particular cosplay. For this dagger, it was for my original-design Lady Loki cosplay, so I took inspiration from Loki’s various knives in the Marvel movies, as well as different fancy knives I saw on the internet. Eventually, I found some things I liked, and sketched out a design onto paper, making sure it was the proper scale. To make it easier, you can also create a design digitally, and then print it out, or you can find different dagger patterns online to use instead.

Foam Dagger Prop

Once you have your pattern down, the next thing to do is to separate it into different pieces, and trace all the different portions of the dagger onto your EVA foam. For this dagger, I separated it into four main pieces: The blade, the cross guard, the hilt, and the pommel. For all of the pieces, I traced them onto 10mm high-density foam from SKS Props. High density foam is great for making props, because it holds its shape really well. I did one layer of foam for the blade, another single-layer for the cross guard, and then double layers of foam for the hilt and pommel, since you generally want the foam to be thicker there. You may need to do more or less layers of foam, depending on how thick you want different parts of the dagger, and how thick your foam is.

Foam Dagger Prop

Once you have all of your foam pieces, the next thing to do is shape them, and then connect them all together. First, glue any of your double-layers of foam together using contact cement. Then it’s time to get out your Dremel. Using a fine sanding bit, carefully smooth down the foam into the shape you want. You may want to use a sharp knife beforehand, to roughly carve out the shape you want, before using your Dremel. Depending on what kind of prop you are making, you may need to Dremel the foam in different ways, but for this dagger, I just needed some smooth shapes. The hilt is smooth and rounded, and I just needed to round off the edges for the cross-guard and pommel. The blade is one of the trickiest parts, since it is so thin, and you have to be more delicate with it. Take your time, and go slowly and carefully to shape it.

Foam Dagger Prop

Once you have completed all of your Dremeling and sanding, you can glue all of the pieces together with contact cement (or whatever kind of glue you choose to use), and then heat-seal the foam. To heat seal it, you simply need to run a heat gun over the entire surface of the dagger. This melts any tiny specks of foam dust, and further smooths out the surface of the foam.

Now, you could just leave your dagger as it is, but it would be kind of boring without any details, right? Not to worry! There’s many ways to add details to foam builds, and here I’m going to show you two. The first one is cutting and glueing on thin layers of 2mm EVA foam, creating some interest for the prop. The second method that I used for this dagger was 3D puffy fabric paint, which I used to draw on lots of intricate swirling details. This really takes the prop to the next level, and adds much more interest. But, again, what type of details you add depends a lot on what kind of prop you are making.

Foam Dagger Prop

Next up is priming. If you don’t prime your foam pieces, the paint will easily crack and flake off, and the prop is much less smooth and durable. There are many different kinds of primers you can use, but my favorite is Flexbond. Flexbond is a great, non-toxic foam primer, that remains flexible under acrylic paint. Add 2-3 layers of Flexbond to your prop, letting it dry in between each one.

Once the paint is dry, it’s time for painting. First, add a solid layer of black acrylic paint over the entire dagger. This isn’t strictly necessary, but I prefer to do it, as it gives you a nice, even base color to work with. Next up is adding all your different colors. The colors on this particular dagger are pretty simple — silver for the blade, gold for the rest of it. You may need to add several layers of whatever colors you add, ensuring that you will have a nice, even coverage.

Foam Dagger Prop

After all your base colors are dry, it’s time for weathering. Weathering helps take your prop to the next level, and adds much more realism. One method of weathering is watering down some black acrylic paint, and brushing it all over the surface of your prop, before wiping most of it off again with a paper towel. You then repeat this step until you’re happy with how it looks, leaving more dark paint in the lower sections, and less dark paint on the raised sections, to add nice highlights and shadows.

Foam Dagger Prop

And once you have completed your painting, you’re done! Your cheap, easy dagger prop is now completed. Now, with your newfound knowledge of foam-crafting — go out and make something cool!

About the Author
Winterstar Cosplay avatar

Winterstar Cosplay


Winterstar Cosplay is a cosplayer, artist, and entrepreneur, who gets way too obsessed over both fictional characters, and new business ideas. After getting started with cosplay in early 2018, she has grown her creative skills to work with foam, fabric, photography, and more, all to bring her favorite characters to life! In addition, she loves to help others create their own cosplays, and does her best to teach them how, through YouTube videos, tutorials, and comic con panels. Winterstar hopes to one day make a living running her own creative businesses.