Manyfold is a free open source Fediverse server type for 3D printing enthusiasts, which lets you upload and share 3D models for prints. It’s intended as a Fediverse alternative to Printables, Makerworld and Thingiverse. Manyfold accounts can be followed from accounts on other Manyfold servers and from Mastodon etc accounts too.
There’s an official demo server at try.manyfold.app ⧉ if you just want to test it, and there’s a full public server you can join at 3dprint.social ⧉ if you want to start a proper account.
If you’re a techy person and want to install your own server, there are instructions for self-hosting on the official website ⧉.