Temporary "Build Mode"

[mindzombies]

Hello, so ive gotten an idea, and nope, i havent searched around for it much, but here is the layout:
Since i run a sandbox server, with lots of different types of players. Some want to just fight, others want to build and show off their creations. To make sure everyone is at peace, i.e the fighters dont keep on killing the builders and annoying them.
So this is my proposed idea to fix it all:

By creating a different 'group' or 'team' for builders, which will give them immunity, i.e god mode, so they can build in peace. Also implemented would be that if they killed someone, then they will be switched back to the default users team. And this team will only be given for some time, i.e half an hour or so. The main problems i see in this is the fact that they can still propkill, which i hope wont occur a lot..

But if any of you have heard of anything similar, or have any idea as to how this can be done, i'd love to hear your ideas.

Thanks

[MrPresident]

In my gamemode I have togglable PVP.

Player types !pvp and can toggle it on and off.
Only players in PVP mode can damage other players in PVP mode.

[mindzombies]

Well, I'm looking for something like that.. Would you be  greatful and share this awesome code with me? That is if you don't mind, and are totally okay with it

Thanks

[MrPresident]

It's integrated into my gamemode pretty heavily. If no one else beats me to it, I could throw together something for you, just not this second.

[mindzombies]

Alright thanks for your help, and if someone does beat  you to the punch, well you can still post yours...

I  wouldn't mind more help (=