Rumi Sword From K-Pop Demon Hunters

Hello everyone, I hope everything is going well. Today I'm presenting a Sword based on the 2025 popular animated movie called: KPop Demon Hunters. This Sword will be made of Paper, Foam and glue.

KPop Demon Hunters, It's a 2025 American animated musical urban/fantasy film that follows a K-pop girl group, (Huntr/x), who lead double lives as demon hunters, battling a rival boy band of demons.

I decided to make this sword since my little sister is obsessed with the character of Rumi, so most likely she will dress up as this hunter for Halloween.

Paper

Hot Glue

Holographic clear Vinyl Laminate Film paper

Eva Foa

Templates

Cola

Mini led strip lights (battery powered)

Analyzing Rumi's sword, I came to the conclusion that apart from the shine and multi-colored tones, it also has some inscriptions which, if observed closely, are constellations.

Later we will see how this will affect my design and maybe yours.

First download the templates.

I designed a 3D model of the sword as close as possible to the design seen in the film with several references and frames of it.

Then, on the Paper Maker page, I converted it into printable templates for assembly.

You can download them below

Print the templates on adhesive paper so you can transfer them to rigid cardboard.

Cut out the group shape and then glue it as directed onto the cardboard.

To form the sword take the linear groups just like the image in this step

Be guided by the numbering on each piece and stick piece by piece on the white cardboard following that numerical order.

Then after joining the first row, which corresponds to one face of the sword (it is made up of 4 faces) join the other group lines that make up one of the 4 faces

remember to follow the numerical order.

If you follow the order correctly you will get a complete piece.

You will have to emboss this resulting piece to create the respective folds. To do this, use a worn ballpoint pen and, with a ruler, press over it to form the fold.

Cut out the resulting piece, in my case I used scissors but for greater precision I used a cutter

Now, to give more detail to the sword, I will highlight the emblematic designs engraved on it. As I mentioned before, this sword is engraved with some of the most famous constellations. But to go deeper, this sword is based on a real sword that existed in Korea, called the Saingeom.

the Saingeom (四寅 劍) or the “four-tiger sword” is forged when the year, month, day, and hour of the Tiger align. Regarded as the strongest spiritual weapon, this highly valuable weapon was used by kings in shamanic rituals to slay demons. the four-tiger sword embodied the authority of the royal family, symbolizing the tiger’s power.

But in my case I decided to do something more personal, when analyzing the constellations and imagining capturing them on paper and then generating the cuts I realized that it was going to be a big problem since many cuts would make the sword wobble and deform, so I chose to design some shapes that simulated the constellations, but using the letters of my sister's name, and since her name is Luciana I adapted the design of the constellations to the letters that make it up.

Then, very carefully and calmly, I cut the spaces to later place internal lighting and get as close as possible to the design of the sword in the movie.

but then I ran into a problem

When I turned the design over, it was reflected and the letters were backwards :S I had designed one part of the sword with her name and the other with a different design, so I had to locate the cut spaces and mark them whit a pencil to make the same design on both sides, so that way you could read my sister's name.

Now with both sides with their respective engravings made, glue the tips of the sword, apply a little glue on the respective tabs

Then, using glue, cover the sword with the translucent iridescent holographic paper.

Glue carefully one side at a time to avoid a mess of glue and paper, as this paper is difficult to handle, especially with glue.

Now, cover the inside with white foam so that the light disperses better.

Measure each side and cut strips of white foam, apply glue and let it dry.

When it is already covered, and with the foam light diffusers, it is time to seal the sword.

Start by applying glue little by little on sections of the edge but not completely.

Each time you apply glue, press down for the time necessary to completely seal that area of the tabs.

Repeat the process until the entire front face of the sword is joined with the back.

After you have the sword blade finished, the next step is to illuminate it from the inside with the LEDs.

At first, I used a stick and wrapped the LED lights around it, but this didn't work because the stick didn't allow the light to disperse evenly and made the sword heavier. So, I had to solve that problem.

Then I thought of a thin tube, and this solved the problem because by putting the lights inside it the light would spread better and illuminate much more.

here you can see the Lighting Test

Now after making the blade of the sword, let's make the handle.

Then take the printed parts and cut them out to then place them on a harder paper/cardboard.

For the handle, there are two types of molds: a structural mold (with tabs, which goes on cardboard) and another that goes on foam.

Structural molds.

This template goes directly onto the stiff paper. Use the ballpoint pen to emboss the lines and create the conical shape of this piece, and then glue tab by tab following the numerical order.

Foam Molds.

For this type of mold, a transfer will be made to a thicker material, either cardboard or EVA foam, with a thickness of 3 mm.

Glue these molds to the golden EVA foam and cut out each piece.

After lining the molds with the gold EVA foam, cut off the excess.

Join the blade with the handle, apply glue and let it dry, follow the simulation in the image to assemble the foam pieces.

Apply glue to join all the resulting pieces. Check the order of the sword guard.

Cut a strip of gold EVA foam and cover the handle in a spiral shape.

Hide the LED switch with a piece of foam. And with this you have completed your tiger sword.

Conclusion:

Despite paper and cardboard being such a delicate material, I ended up with a sturdy prop that's functional for Halloween parties or any cosplay presentation.

Thanks for checking out my project.