Is it possible to construct a working/usable violin out of cardboard?
I know I sound insanely stupid, but I'm kind of serious.
Could you actually pull it off?

usable..probably.

pleasing in the slightest to the ear...not possible.

carboard and wood are just not the same.

sorry.

Yes its possible I've seen a clip on youtube with violins made of paper.

ive seen one commisioned by a metal smelter, it was full steel. sounds banjo-y

Here's the link http://www.youtube.com/watch?v=7g4yBIEZvRc Doesn't sound so bad either. That's probably laminated paper. Cardboard can be surprisingly stiff with proper construction and I've read about HiFi-loudspeakers made of corrugated board which actually sound good. In this construction cardboard acts as the "cone" (flat though) of the speaker with an electromagnetic "motor" basically glued to a suitably formed cardboard box, so it might be resonant enough for a violin top also. But some parts like tailpiece,bridge and pegs probably can't be made of cardboard. Interesting idea really.