Cheshire collimator for newtonian telescope (Q66204)

This eyepiece is used to collimate your newtonian / printonian telescope's primary and secondary mirrors. Inspired by this laser collimator, http://www.thingiverse.com/thing:12624 but here there is no need to collimate the collimator ;-) . Use: several tutorials online, I especially like this one: http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm check also this: http://www.atmsite.org/contrib/Carlin/collimation/kolli2.htm#mkcombination and http://www.skyandtelescope.com/howto/diy/3306876.html