FOSS gamedev and creative worlds

How about a new privs system where everybody may reserve a small area and everybody could only build/destroy in his own area?

I believe there are one or more mod(s) that accomplishes this.
I do not use them, personally, so I do not know what they are called.

Search for "node protection" or something like this in this forum.

sounds like you want Node Ownership

Is there any server having that?

or mod protector, i use it on my server