Flashback: Gory Brain Cap

Costumes, Cosplay, and Props Craft & Design
Flashback: Gory Brain Cap


By Jeromina Juan

If you’ve been brainstorming Halloween DIY costume ideas, no need to bang your head on a brick wall. It’s time to put on your thinking cap. Literally! With just a ball cap, squiggles of caulking (the stuff made for sealing tubs, sinks, and windows), and dabs of paint, this bloody brain is yours to wear on fright night.

It’s best to study pictures of the human brain before tackling this project in order to best mimic the brain’s convolution patterns when caulking the cap.
Weighing a little less than a pound and a half, this costume is still lighter than most professional bicycle and motorcycle helmets. Use a cap without an adjuster to ensure a perfect fit.

For a PDF of this tutorial, visit the build page on Make: Projects.


Fitted cap, without adjuster
Craft knife or seam ripper
Acrylic paint
, red and black
, approximately same size as cap
Tall jar
Plastic bag
2 tubes of latex or acrylic caulking (not silicone)
*, ivory or bone color
Caulking gun

*NOTE: Silicone caulking is not paintable.


Brain Cap Step 1.JPG

Step 1: Remove the cap’s brim by carefully ripping the seams with a craft knife or seam ripper.

Brain Cap Step 2.jpg

Step 2: Place the cap on newspaper. Paint the cap with dark red paint (a mixture of red paint and a little bit of black paint). Let dry.

Brain Cap Step 3.jpg

Step 3: On newspaper, create a work stand for your cap by placing a bowl upside down over a tall jar. Place a plastic bag over the bowl, and the cap over the plastic bag.

Brain Cap Step 4A.jpg

Step 4: With a craft knife, cut the tip of the caulking tube to have an opening approximately 1/2″ in diameter. Load the tube into a caulking gun.

Brain Cap Step 5.jpg

Step 5: Caulk convolutions on one half of the cap to create one hemisphere of the brain. Repeat on the second half of the cap.

Brain Cap Step 6.jpg

Step 6: Let the caulking dry for approximately one to two hours until the surface loses tack. Wearing gloves, lightly press on the convolutions to slightly flatten the surface.

Brain Cap Step 7.jpg

Step 7: Let the caulking cure for 24 hours.

Brain Cap Step 8A.jpg

Step 8: Once the caulking has cured, mix water with red paint and a little bit of black paint, to a thin, runny consistency. Use a brush to dab paint mixture onto the caulking, focusing on crevices. Apply a second coat if needed. Let dry.

Brain Cap Footer.JPG

Your bloody brain is ready to wear! You may wrap gauze to cover the seam between the brain and the forehead. Of course, the more fake blood, the better! Happy Halloween!

About the Author:


Jeromina Juan is the brains behind the blog Paper, Plate, and Plane, where she shares unique DIY ideas for all holidays throughout the year. She is partial to Halloween, being born on this special holiday.

2 thoughts on “Flashback: Gory Brain Cap

  1. Jessica says:

    I am SOOOOO making this! ASAP for Halloween!

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Haley Pierson-Cox from Red-Handled Scissors is a maker of crafts, a lover of cats, an avid swearing enthusiast, a cross-stitch book author, and a general purveyor of quirk. She's also sometimes an irritable cartoon named Tiny Cranky Haley. https://www.redhandledscissors.com

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