Makerbot

http://www.makerbot.com/blog/2013/02/22/replicator-2-extruder-alternative-some-spring-in-your-step/

http://traverseda.wordpress.com/2014/05/23/makerbot-blatently-steals-and-patents-a-community-design/

http://www.makerbot.com/legal/patents/

https://www.google.com/search?tbm=pts&hl=en&q=makerbot

http://www.reddit.com/r/3Dprinting/comments/26bt91/makerbot_steals_yet_another_design_we_need_to/ if anyone has not already seen this. Makerbot seems to have also patented an auto bed leveling design from Steve Graber, the guy who designed the Cerberus line of Delta 3D Printers.

http://www.openbeamusa.com/blog/2014/5/22/stay-classy-makerbot

Quick release extruder
http://www.thingiverse.com/thing:7129

http://www.freepatentsonline.com/y2014/0120196.html

https://plus.google.com/+jwildeboer/posts/hsQRqmWXD4y

http://www.makerbot.com/blog/2013/02/22/replicator-2-extruder-alternative-some-spring-in-your-step/

http://web.archive.org/web/*/http://www.makerbot.com/blog/2013/02/22/replicator-2-extruder-alternative-some-spring-in-your-step/