The lovable, curious, sentient, walking AI tanks of death from Ghost in the Shell Stand Alone Complex.  The Tachikomas are only characters in either series who the audience develops any emotional attachment to at all.  And they kill them horribly... twice.  
Now you can build your own very own Tachikoma.  It will loyally follow you on your adventures, while inquiring cheerfully about the meaning of life and the nature of its own existence.  
(Remodeled for 3d printing based on the excellent work of ALM Model Works on 3d Warehouse)  
(Update 1/19/2015 - I have added a thin shelled version of the Tachikoma for people who would like to replicate my experiments using a Form 1+)