This site seems a bit dodgy, it’s telling people that Reddit’s 3D printing community has “relocated” to some random Lemmy site that seems dead other than one person just filling it with posts simply titled “balls”.
I don't think that necessarily makes sub.rehab dodgy, they are accurately communicating alternatives both mod-endorsed and not.
https://old.reddit.com/r/3Dprinting/comments/14a7sh5/join_us...
The 3dprinting communities on other Lemmy instances are plenty active though.