https://www.techradar.com/news/reprogrammable-braille-could-be-the-key-to-ebook-readers-for-sight-impaired-people

Researchers from Harvard University have developed a framework to encode braille dots onto a blank material, which could be the first step towards creating a braille ebook with just a single reprogrammable 'page'.

It's a simple principle: a thin elastic shell is compressed by a force from either end, and indents are made by poking the shell with a stylus. The indents remain after the force is released, and can be erased by stretching the shell flat again.