We love Paper Source, and we love free pattern downloads. The math's pretty simple, then -- we really love this paper rosette project from Paper Source (pdf).
All you need is some nice 8 1/2" x 11" paper and pretty ribbon or string (Paper Source is great for both) to make these sweet and simple rosettes. The project doesn't involve much more than folding sheets of paper accordion-style -- no scissors required! -- so grab your nieces and nephews or the neighbor kids and make a fun afternoon of it.
The finished products will look gorgeous hung from trees for an outdoor wedding, or on the supports of an outdoor tent. For an indoor affair, hang the rosettes from the ceiling at different heights or off the centerpieces.