they're made of wood/plastic and lots of crummy foam usually. They definitely wouldn't last good in a crash and any MOT tester you took it to would definitely give you a funny look..
Try it with a crash test dummy, timber and plastic great in a crash, we will start a collection on here, just let us know what you decide
don't forget to wear a crash helmet, see you in heaven one day, merry xmas, downright mad and stupid idea 
'usually' ? I would have thought even the crappest ones would have a metal structure and thanks for thinking I'd actually be stupid enough to consider one that didn't have a decent, strong metal frame.
And what's all the discussion about crashing? I've never considered my car seat to be providing any sort of protection in a crash, there's only the front two bolts holding a seat on anyway. The only thing I've thought of is if you are rammed from behind when you'd need the seat hinge and the back of the seat to be structurally sound and hold your body weight.
What do you think would happen in a crash? that the seat would just magically come loose and crush you against the windscreen with it's crazy momentum? It can be reasonably assumed that the seat would be reinforced and that it is bolted to the body at least as well as the standard one is.
As far as I know, no one has!!!
(and for very good reason!!)
They won't have been crash tested, will contain bit that will injure you in a crash, generally everything!!
Save some more money up and buy proper seats.
and if you are in a crash to the point where you think knives are going to start flying out of the seat then there's probably many other parts of the car about to crush/kill you anyway. As long as it's bolted down then the seat belt should do it's crash protection job and hold you against the seat.
I just want to point out I'm not planning on doing this, just I was in staples one day and saw the really nice office chairs (like in my first post) and having just been sat in the mini I thought having a nice leather chair with arm rests wouldn't be too bad.
I know it sounds like a stupid idea but I've been going through why it wouldn't be possible and seem to come up with a way to at least make it as structurally sound as the seat it's already got.
Edited by bluesprite, 17 December 2011 - 08:52 PM.