Combining multiple STL files I have a collection of STL files, each containing a separate moving part of an object I want to print. (Imagine a set of gears, or similar, that prints as a single object with multiple moving parts.)

My plan was to import them all into Cura, then hit print, then take my fully assembled object off the build plate. However, Cura ignores the coordinate system in the STL files and automatically separates the components from each other on the build plate. This is usually helpful, but it isn't what I want in this case.

So I'm looking for a quick and simple way to combine my multiple STL files into a single STL file. I know that the objects don't overlap, so I don't need to do a CSG union operation - it's enough just to concatenate the objects.

I tried OpenSCAD, which works, but it takes a really long time, because the meshes are fairly complex and it does the full Boolean operation. Is there another quick and simple way to perform this task?

I'd prefer a command line utility, but I'd also be happy if there's a quick and simple way to do it in some free graphical software. (However, I don't want to spend time manually positioning the objects - they're already in the right places in the STL files, so I just want to import them and go.)

Edit I've accepted Trish's answer (use Blender), but I'd still appreciate a command-line option if anyone knows one.
The operation you want is almost just cat'ing the files together. However you need to remove the 80 byte header from all but the first, and add up the 32-bit triangle count from each file immediately after that. Output should be:


Copy of first 80 bytes of file 1
Sum of int32 from offset 80 of each file.
Bytes 84-end from each file.


See https://en.m.wikipedia.org/wiki/STL_(file_format)