I'm not sure where I originally heard about it (probably this list), but a while ago I found some very useful command-line tools for manipulating STL files: https://github.com/AllwineDesigns/stl_cmd I contributed some code to it to allow converting between text and binary STL files, and added an stl_zero command which centres an stl, either around the origin, or with the lowest point at z=0. It is VERY useful if you do a lot of work with pre-existing STL files