I'm not sure you can call it a costume, since it's nothing more than black electrical tape. And since it's 'mainstream', they aren't exactly what we would call 'busty'.
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The Black Tape Project is a scintillating visual extravaganza that has captivated audiences around the globe. Prepare to be mesmerized as the barriers of creative fashion are pushed to their limits.
The Black Tape Project is an exclusive fashion experiment which attempts to creatively display the sensual nature of the human form as it vacillates between the realms of innovation and seduction."
In other words, create designs on sexy women using nothing more than black electrical tape.