Can you tell us a bit more about the cardstock you have? There are so many different kinds out there. If it is a thinner kind that doesn't crack on the first Crease you might well be able to fold simpler models. There are for example a whole lot of business card Origami models of whom I think should be possible to fold with thin cardstock: http://www.origami-resource-center.com/ ... igami.html
Furthermore it might be possible to wet fold it, to prevent it from cracking.
Just experiment a bit to find out what is possible and what not.
the type of cardstock I have is a bit bore thinner and doesn't crack, something like the one I bought at walmart, and it is foldable and i tried to make a crane and came out great.
Anything with curved creases will work wonderfully in cardstock, with a bit of wetfolding. Check out the curved folding Flickr group for ideas: http://www.flickr.com/groups/783444@N25/
Are you kidding me, they work so well! Though modulars don't take too much creases for each unit, cardstock is my favorite material for modulars. My favorite model to use it with is the F.I.T. as it is super sturdy!
Laugh alone, and the world thinks you're an idiot.
On the other hand if you have a bunch of it, theres a lot of uses including all that has been said, and a kool program called "Pepakura". Although the designer portion of the program is premium, the free portion of it allows you to download files and use them. It allows you to take a 3D file flatten in to a printable constructable pattern,after assembly it should accurately replicate the very 3D model that was used.
Laugh alone, and the world thinks you're an idiot.