Datshiane Navanayagam meets two engineers who want more women to become inventors. Roma Agrawal is best known for her work on The Shard, the UK’s tallest building. She’s also the author of Nuts & Bolts, a book which explores the history of seven tiny but fundamental inventions that changed the world, and the role that women play in scientific innovation.Nzambi Matee is a Kenyan inventor who produces sustainable low-cost construction materials made of recycled plastic. Her company is called Gjenge Makers.Produced by Alice Gioia and Emily Naylor for the BBC World Service.