It is perfectly fine to save another persons build without permission. It is even alright to host that save in your own server. Why don't you people understand that client saving exists for that reason. Stealing is when they claim it as their own, not when they use it for their own fun.
Yes, exactly, save whatever the hell you want, whenever the hell you want, just make sure people know you didn't build it, and that someone else did.
Also, you might not want to save and host car or jumping challenges that someone else made, that I consider full thievery.
