adding a roll cage?

How do u add a roll cage to a car like the fujimi FD3S RX-7?, and what materials would u use to do it?

About the material, I would use styrene tubes or copper strings.
You heat the styrene profiles with a flame and then bend them to shape. Copper is easy to bend because you can do it without the help of any tools but must be soldered, I've never tried to glue copper, I think it won't work. There was a tutorial on BMC, I search the link.

Edit: http://www.briansmodelcars.com/tutorials/tutorial.asp?TutorialID=13&CurPage=1

what about super gluing the copper?

if you try the super glue on cooper it must be a perfect joint and that is very hard to do. It is much easier to solder it, that is no problem at all and the joints will be perfect. Soldering tool is very cheap and you always need one, just buy the one with thin head with trigger switch and some soldering wire (thin) and you can do it in 20 minutes. I think that would be the easiest method by far. Just watch out for fingers because cooper is heated in seconds ;)

I think you can use putty on copper, it holds on to pretty much anything :)

ok thanks i might borrow a soldar from friends or i might go with putty. if it works like u said.

but wont the heat from the soldar melt the plastic mold of the model?

i tried to solder copper once and it wouldnt stick?

ummm i think u need to sand it down a little. I tihnk i've done something like this at school(not sure though)