This handy Japanese tool featured on Paper Forest, the Harac, has a tiny rotating blade and an ergonomic handle for cutting complex designs in paper. Paper Forest recommends purchasing them through paper companies like Soolip, although according to PF's comments, they won't be getting them in until July. If you read Japanese (or can find someone who does), you can order them here.

I'm going to keep my eye out for one of these. You can get a bunch of the tools, and start doing "paper architecture" projects like Ingrid Siliakus. Paper architecture is the art of creating sculptures out of one piece of paper. It might take a couple tries before you get this detailed though...