On first inspection ferro fluid is easily mistakable for oil, given its dark colouration and ability to flow. But when placed in a magnetic field, it becomes a gel and forms complex geometrical patterns that reflect the magnetic field lines. These rippling, intricate geometries take shape because ferro fluid is composed of 1) a liquid - typically an oil – which allows it to flow when there is no magnetic field, and 2) nanoparticles of iron oxide that align with a magnetic field to restrain the fluid flow. Ferro fluid is a mixture of solid and liquid using an emulsifier to ensure they mix together perfectly to achieve this unusual material behaviour. Ferro fluid was developed in collaboration with NASA in the 1960s to address the issue of moving fuels in zero gravity. Today it’s used in lubricants, as a seal in hard disks, and car suspensions. Ferro fluid also has a strong following of artists who apply its unique properties to generate unique shapes in their work. Explore ferro fluid on the Institute of Making website: https://www.instituteofmaking.org.uk/materials-library/material/ferro-fluid.