Nice building you got there!
Impressive!
Hey Survivor. You used to play a lot on Atmos didn’t you? Nice building
Welcome to the forums! 
And nice building 
I think Unihorse still has credit, but I’ve heard it crashes frequently. Don’t know if that’s an issue.
Pixmilla has credit, but it’s more pixel art than building usually.
I don’t know if Creative of Time has credit still, but it’s another building world.
Then Rabbithole and SGE (Neither of which I’ve been to, but if I remember correctly they’re both building worlds with credit).
Plenty of Mac servers too, I imagine (though I haven’t really visited any, so I don’t personally know).
This list by Thuthu Is absolutely immense and should help you to find a few more worlds.
Yep, there’s still credit for a good long while before I have to add more! The crashes are still an issue though.