The Papercraft ones are for the experts and take forever (but look incredible):
http://www.yamaha-motor.co.jp/global...aft/index.html
This has to be built to be believed:
http://www.scitoys.com/scitoys/scito...aper_ring.html
It took me ten years, an old origami book and the help of this site to build the Jackstone:
http://anools-origami.tripod.com/jackston.htm
Last one, maps should be folded like this (Miura-Ori folding):
http://www.u3p.net/fold/pliage_a.htm
http://www.britishorigami.org.uk/theory/miura.htm