How can I run two instances (or equivalent) of Slic3r on OS X?


I am modifying some Slic3r config parameters and comparing the results. How can I have two instances (or equivalent: I would like to see two model windows with their associated configuration screens) of Slic3r at the same time? I'm on OS X, but if there is a generic (e.g. within Slic3r) solution that will be preferrable.

Mark Harrison

Posted 2018-11-05T00:58:59.340

Reputation: 923

Mark, The answer to your question is available here:

– Samveen – 2018-11-05T05:01:00.993

Thanks Samveen, much appreciated! I think you should consider that it might be useful here to answer questions related to running 3D printing software, such as slic3r. There could have been specific slic3r commands or configuration options that are useful for doing this. Cheers and thanks again! – Mark Harrison – 2018-11-05T06:18:23.380


@Samveen If you look at Game plan - What is on-topic? I'm inclined to say that this falls in the category of "Software issues" and should not be closed.

– 0scar – 2018-11-05T07:48:25.397

Yes, this could go anywhere including Ask Different, SuperUser... however, we have an answer now, and everything is upvoted, so even if it is closed, then it will never be deleted :-) – Greenonline – 2018-11-05T08:29:41.553

2@MarkHarrison however, this is very much purely a question of how to handle executables under OS X. the fact that you are dealing with Slic3r is irrelevant. Now, if you want to ask how to make Slic3r do two different slices on one object at the same time, then this would be on-topic. – Carl Witthoft – 2018-11-05T18:58:13.790

@CarlWitthoft, good point... I've updated to reflect that I wish to see two model windows and associated configuration screens, without suggesting or requiring it be done by running multiple Slic3r processes. – Mark Harrison – 2018-11-08T22:20:38.097



From a terminal window, run the command

open -n -a slic3r

Each time the command is executed, a new instance of Slic3r is created.

As per Carl's note, keep in mind that both instances of Slic3r will be sharing the same configuration files, so it will be safest not to save configuration changes while both are open.

Mark Harrison

Posted 2018-11-05T00:58:59.340

Reputation: 923

1See comments about Prefs files under Greenonline's answer – Carl Witthoft – 2018-11-05T19:01:01.543


You could duplicate the application by clicking on the application and pressing Command (⌘) + D, and then run both - although I'm not sure if that would mess with the preferences. I haven't fully tested it, but both instances opened up and worked, seemingly ok.

Duplicate applications

You could even rename them to something other than "Slic3r" and "Slic3r copy" to remind you which application is slicing which model, for example:

  • "TestCube" and "Benchy", or;
  • "Slic3r-TestCube" and "Slic3r-Benchy", or whatever.

However, Mark's answer seems much more elegant.


Posted 2018-11-05T00:58:59.340

Reputation: 5 004

1So far as Preferences and whatnot go: that depends on whether Slic3r stores all config files inside its own application folder or in /usr/lib/[whatever] . However, if one follows Mark H's answer, you'll guarantee that whatever changes to config or prefs you do in either instance will change the only existing prefs. files. That makes your answer slightly safer! – Carl Witthoft – 2018-11-05T19:00:45.147