Spin chain. The same as [earlier model](https://sketchfab.com/models/a3ce79a459cc4849868eb2ab508dbd80), but in obj format to test [facebook gltf](https://developers.facebook.com/docs/sharing/3d-posts/glb-tutorials). Yes, now it [does work](https://www.facebook.com/alexander.y.vlasov/posts/1882694975106724).