In a video, the model was covered in slimy gray plaster to create the mystery costume.
Heidi Klum shared a snap showing her covered in sticky gray plaster as she prepared for this year's Halloween.
The supermodel wore just a horn on her head as she stood still while a team of workers covered her head to toe in goo.
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A time lapse video shows, a hair dryer are used to speed up the process.
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Heidi won't reveal what her costume will be when it's finished saying only on Instagram:
Klum is known for her wild Halloween outfits that make her unrecognizable to the public. In the past she has been an old lady, Cleopatra, a cat, a falcon, and an ape.
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