Here are 3 of the best know 3D printed humanoid robots. While most of them are too expensive or complicated to be used in a school classroom, they show what is possible with 3D printing and robotics.
Jimmy is an open-source humanoid robot created by a collaboration between, Intel, Trossen Robotics, and Olin College. Though a very capable robot, Jimmy costs around $16,000 to purchase, which puts him out of reach of most k-12 schools.
The original PLEN humanoid was launched in 2007. But in 2015 PLEN-2 was presented on kickstarter. The robot is intended by its creators to "humanize robotics." Not difficult to consider watching the little robot.
An open-source project created by a french sculptor, the InMoov is one of the best and most difficult 3D printed humanoids to build. With several hundred pieces and cost of thousands of dollars it is not be the casual builder. But with capabilities such as speech recognition and visual tracking, it is an impressive machine.
The Poppy robot is a humanoid open-source project that is still developing. At this point it can't walk without assistance. This is really a robot for programmers. Its face and limited capabilities leave a lot of room for development and design of new capabilities.