How is this different from cloning (for example) open source licensed software? There is plenty of OS philosophy that says that even people who clone and close

How is this different from cloning (for example) open source licensed software? There is plenty of OS philosophy that says that even people who clone and close-source the technology bring ancillary benefits to the project - for example by driving market adoption of a similar platform (and thereby attracting users looking for the similar-but-free option). Presumably MakerBot chose their license with eyes wide open. That the project has been successful enough to spawn TangiBot is purely a sign of MarkerBot's success, not of dirty dealings on Matt Strong's part.