mbotmake
A gcode to .makerbot conversion tool, compatible with Marlin gcode from Cura. And likely others.
This is a fork that works for the Makerbot Replicator+, and it is unclear if it still works for the 5th Generation. See the original repository if you have a 5th gen.
Usage
It's a Python script that generates a .makerbot file from a .gcode file that is passed as an argument on the command line.
You are almost guaranteed to have to understand the makerbot file format anyway, so just read the code.