Free building shapes STEM cards. Great math center or STEM box for kids. I love that there are 2D shapes too.
TinkerCAD is free, web-based 3D modeling software that allows you to easily create your own models and export .stl files for 3D printing. It's even easy enough for elementary-aged students!
Models for fully printable parametric music box. 3D printer.
INFOGRAPHIC: Exclusive Tips on Maximizing Your Income from 3D Print Models - Blog- CGTrader.com
Low-Poly, Non-Isometric Worlds by Timothy J. Reynolds
Save this one for the Science Fair! How to DIY a 3-D Model of an Animal Cell. CraftsnCoffee.com.
AQ Medicare - What can be used in a 3D Printer?
Top 10 Websites to Find Free 3D Printing Models for your jobs and hobbies
(Realistic articulation) Maybe something for Printer Chat?
3D Printed Modular Hanging Tool Organizers by Matthijs Kok for Cubify