Rivnuts - how to?

[Error404]

I need to install a hexagonal rivnut into a new piece of inner wheel arch i'm replacing on the coupe - one of the rear bumper bracket mountings

how do they work? Do I need a special tool / gun to install them?

[saltinot]

You're going to need a special tool. It resembles one of those large heavy duty rivet tools.

I took my wings to the body shop and just asked them to help me out. They did it au gratis.

I was considering putting some nuts and washers together to get the job done, but just decided the body shop route was easier.

[MattS2]

It is possible to install them without the correct tool, it all depends on the size.
You need three sets of hands though.

[Error404]

thats useful guys, cheers.. The car can't move for the time being so taking it somewhere is out - definately not buying a tool for just the 1!
wonder whether it might be easier to use a round type rather than the hex which i have from audi - it looks fairly heavy duty... i guess drill slightly smaller than the hex, and then bash it in and use the two spanner method.
Luckily I have 3 hands so that should come in handy