Is there a way to save your props?

So, I made a really nice car. Is there a way to save it to my list of props so I can spawn it quickly whenever I make a new save?

Advanced Duplicator

And how exactly do I get that?

Getting Wire off SVN

So… wiremod? Thanks for answering!

Advanced Duplicator (Wiremod version) does like to make constraints a lot weaker when duping. If it does that, remember to freeze the whole contraption before duping. (2 addons to freeze your contraptions with if you make large contraptions: http://www.garrysmod.org/downloads/?a=view&id=12946 http://www.garrysmod.org/downloads/?a=view&id=110776 <- I prefer the last one, nocollide all multi)
I personally use advanced duplicator 2 as it has a better interface and saves a lot better. Not a lot of servers use it yet though.

I’m not really into advanced building YET
By constraints you mean things such as weld, axis, ball sockets, etc right?