Background: Magneto-optical Kerr effect (MOKE) microscopes are powerful experimental tools to observe magnetic domains in magnetic materials. These devices are, however, typically large, unportable, and expensive (∼ several million yen), and therefore prevent many researchers in the field of materials science from easy access to study real-space images of magnetic domains.Methods: To overcome these issues, we utilize data from ”The OpenFlexure Project” developed by the University of Bath and the University of Cambridge. The purpose of this project is to make high-precision mechanical positioning of the studied sample available to anyone with a 3D printer, especially for use in microscopes. We built a low-cost and portable MOKE microscope device by a 3D printer. We redesigned the 3D modeling data of an ordinary optical microscope provided by The OpenFlexure project and incorporated additional elements such as optical polarizers and an electro-magnetic coil into the primarily designed microscope that did not originally have these elements.Results: We successfully observed magnetic domains and their real-space motions induced by magnetic fields using the palm-sized low-cost MOKE microscope, which costs approximately 20,000 yen in raw materials to construct.Conclusions: Our methodology to assemble a low-cost MOKE microscope will enable researchers working in the field of materials science to more easily observe magnetic domains without commercial equipment.
