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Personal Project • cosplay | October 31st, 2025

Hornet Cosplay [HK: Silksong]

An EVA foam mask and a self-drafted cloak to become Hornet from Hollow Knight Silksong, made in one long weekend for Halloween.
  • cosplay
  • fabrication
  • sewing
  • Technologies
    Contact cement, Craft foam, EVA foam, Gesso, Interfacing, Plasti Dip, Sewing machine, Spackle, Worbla
A person in a white Hornet mask with two tall horns, a red cloak with a high collar, black bodysuit and black boots, posing on a wooden staircaseThe same Hornet costume from a three quarter angle on the staircase, one arm raised

Context

I put it to a vote on Twitter and y'all picked Hornet from Hollow Knight: Silksong. So I complied!

Hornet is a pretty simple silhouette: a white mask with two long horns, a red cloak, and her needle. Simple silhouettes are deceptive though! When there are only three shapes, every one of them has to be right.

Silksong key art of Hornet mid-lunge: a white mask with two long horns, a red cloak flaring behind her, her needle thrust forward and a loop of silk trailing through the air

The mask

Patterning

The mask is the whole costume, so I started there. I studied the shape from a bunch of angles, then drew myself a pattern and cut it out of EVA foam. EVA foam is the cosplay go-to for exactly this kind of thing. It's cheap, it cuts with a craft knife, it curves when you heat it, and it glues to itself with contact cement. What's not to love!

A sheet of gray EVA foam on the floor with the mask pattern drawn and partly cut out

Gluing it up (and messing it up)

I had the whole mask cut out and glued together before I realized the horns were too close together!

The glued gray foam mask from the side, showing the two horns and the eye holesThe glued gray foam mask from the front on a cluttered desk

Fixing it properly would have meant drawing a whole new pattern and starting over, and I was not doing that. So I cut an almond shape out of either side of the mask, spread the horns apart, and contact glued it all back down. I also cut a diamond out of the front, right between the horns like the star on a horse's forehead, to help push them apart. You can see it in the fitting photo below. That fixed the horns! It also left dimples along the seams, so those got filled with spackle.

Foam on its own is floppy, so I lined the inside with Worbla to stiffen it up. Worbla is a thermoplastic sheet that goes soft with a heat gun, so you can press it into the inside of the mask and it holds the shape once it cools.

Even reinforced, the whole thing still has enough give that I can squeeze my head into it and it springs right back!

A mirror selfie wearing the raw gray foam mask over a black t-shirt in a messy room, with the diamond cut visible on the front between the horns

Sealing and painting

Foam and spackle both drink paint, and every seam and patch shows through if you don't seal them. So the points of contact and all the spackle got lots and lots of gesso. Lots!

The foam mask with white gesso brushed over the seams and the spackle patches, sitting on a desk covered in tools

Then the whole thing got a coat of white Plasti Dip, which is a flexible rubber coating that seals the foam and lets the mask keep bending without the paint cracking. On top of that went a primer, then a white glossy paint.

The mask painted white, drying on a cardboard box on a tarp in the gardenThe white mask on the cardboard box from the side, with the horns in profile

The finished glossy white mask on the box, horns up, with the eye holes still open

Last step: the eyes got covered with transparent black fabric. They read as solid black from the outside, and I can still see out!

The cloak

The pattern

I made my own pattern for the cloak too. Hornet's cloak is basically a big circle with a hole in it for the neck, plus a tall collar that stands up around the face. Cut out on the floor at midnight, as is tradition!

A paper pattern for a circular cloak laid out on a wooden floor, a large ring with the neck hole in the middle and three curved collar pieces beside itA single curved paper pattern piece on the floor

Choosing the fabric

I went back and forth between a ton of reds at the fabric store! I ended up with a thick weave that gives the cloak some heft, so it hangs and swings like a real garment instead of floating around like a costume. It's also warmer than the other options, which I did not regret on Halloween night.

Three bolts of red fabric in slightly different shades and weights leaning against the shelves at a fabric store

Wearing the finished red cloak with the high standing collar, arms out, without the maskThe back of the red cloak, showing how it drapes to the elbows

The collar is the one part of the cloak that can't just hang. It stands up around the face like a cone, so I gave it a layer of craft foam and interfacing on the inside to hold the shape. Fabric alone would have flopped over by the second photo.

Underneath, I bought a black body suit and wore black boots. That's the entire lower half of Hornet. She's a shadow!

A selfie in the white mask and red cloak, indoors

The needle that wasn't

Hornet's needle is a giant sewing needle she uses as a sword, and I really wanted to make it! But the mask ate way more time than I anticipated, and by the time it was dry I was out of weekend. So no needle this time.

Final costume

Start to finish, the whole thing only took one long weekend! Here's Hornet out in the wild on Halloween night.

Hornet at a party at night, the red cloak lit purple by string lights, with other guests behindHornet on a porch at night, the mask glowing under purple lights

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