GeekMomProjectsFound a magnet-activated, battery powered LED board+controller on AliExpress (https://a.aliexpress.com/_mNudMLl) and turned it into a (chunky) ring with a quick 3D print:
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.