Four years ago, Mark Corliss, a tattooist in Yarmouth Port, Massachusetts, was covering up a woman's scars with flowers when she begged him to do nipple tattoos.
Corliss told BuzzFeed News he was "very intimidated and nervous but nonetheless decided to figure it out" for the breast cancer survivor.
Since then, Corliss has been offering the service at no cost for breast cancer survivors who have gone through a mastectomy and has done at least a couple hundred sets.
Last week, after chatting with a woman and learning that 3D nipple reconstruction can cost $800 per nipple, he posted a photo of a set of nipple tattoos on Instagram, asking people to share it because "these women should not have to pay a ridiculous fee to feel whole again."
His post was then picked up by several Twitter accounts and has since gone viral.
Kassy Cho is a reporter for BuzzFeed News and is based in London.