Gina Häußge / @foosel

3D Meetup Sweden 2019

Who am I?

Gina Häußge aka foosel

  • Fun fact: the ß is pronounced like an S
    (there is no B there, really!)
  • Creator & maintainer of OctoPrint
    and mostly sole developer
  • Passionate coder 👩‍💻
  • Former IT Consultant & Software Architect
  • Owner of a 3d printer since late 2012
    (help, they keep multiplying!)

Why did I create OctoPrint?

First printer acquired in November 2012

  • Obviously wanted my desk back
  • Rough idea how to solve this:
    • Web interface
    • Server installed on a headless Raspberry Pi
      (had just come out that year)
    • Put printer in spare (bath) room
    • Remotely monitor full print via WLAN
  • Problem: existing solutions treated printer as write-only
    • Connect
    • Upload a file
    • Hope that it prints
  • I didn't trust that at all, no feedback
  • Wanted to at least
    • track temperature
    • track progress
    • ideally provide webcam view
How hard can it be?
— Famous last words
  • Sat down & built first version over Christmas 2012
  • Published my little pet project, figured "I'm done"
  • People started messaging me about it
  • Then it took over my life
  • And now I've been working on it for the past six years
    (Honestly I'm still unsure how this all happened...)
  • Learned a ton

Challenge #1

No proper protocol specification

The "protocol"

  • Organically grown dialect of GCODE
  • GCODE:
    • (standardized) programming language for CNCs from the 1950s
    • plain text file format
    • nothing about sending messages over serial
    • no error correction
  • Communication protocol stuff hacked on top

The "protocol"

  • More or less accurate general documentation in the RepRap wiki
    • Living document
    • Anyone can edit it
    • No governing body
  • Marlin (mainline) specific documentation on 👍
  • General problem with both:
    • No test suite or reference implementation
    • In general no definition of command responses


  • New firmwares or forks with
    • New commands that have incompatible meaning elsewhere
    • Common functionality in a slightly different or outright broken way
  • Example: possible (simplified) temperature reports
    ok T:20.3/0 B:20.2/0                      ; Marlin & Repetier, single extruder
    ok T:20.4/0 T0:20.3/0 T1:20.4/0 B:20.2/0  ; Marlin & Repetier, multi extruder, 
                                              ;   T1 active
    ok T:20.3/0 T1:20.4/0 B:20.2/0            ; Smoothieware, multi extruder
    T:20.3/0 B:20.2/0                         ; autoreport or blocking heatup
    T:20.3/0                                  ; autoreport or blocking heatup
    T:20.3                                    ; blocking heatup?
    ok ==T:20.3 /0 ==B:20.2 /0                ; Creality CR-X 🤨
    echo: T20.3 /0.0 B:20.2/ 0.0ok            ; Lerdge S 🤦‍♀️


  • Regularly need to read firmware source of forks
  • These days increasingly difficult (China...)
  • Last resort: Logs from & close collaboration w/ users
  • Have to draw a line somewhere w/rt broken firmware
  • Attempt to standardize: Strong resistance 🤷‍♀️

Please scream at your vendors if they break widely supported behaviour and not at me, I'm on your side 😉

Challenge #2

Fragmented firmware landscape

Fragmentation left and right

  • Most users rarely update their printer firmware
    • if they even can!
  • Vendors fork and never merge from upstream again


  • Ancient bugs still present in current printers
    I still get tickets regularly caused by bugs in Marlin forks I fixed six years ago
    • Missing oks
    • Translated serial messages
    • Broken resend requests
    • etc
  • Takes ages for new features to propagate
    If they propagate at all
    • E.g. busy protocol
    • E.g. capability reports


  • OctoPrint has to accommodate firmware
    • from today
    • from 7 years ago
    • and from anything in between
  • Next to no way to differentiate between those
    • Marlin V1; Sprinter/grbl mashup for gen6
    • Author: (default)
  • ➡ Complex code to handle printer communication

Please update your printer's firmware regularly - and ideally run the mainline version, not an (outdated) vendor fork 😉

Challenge #3

Plugins require backwards compatibility

Plugins in OctoPrint

  • Since OctoPrint 1.2.0 (~2015)
  • Users can easily add or modify functionality
  • Currently over 160 plugins registered on the repository
  • Advantage: Easier to customize OctoPrint to your specific workflow
    • Not everyone wants every feature
    • Just pick what you need
  • Advantage: Bundled plugins are also easier to maintain
  • Disadvantage: Easy fixes turn into backwards compatibility nightmares


  • Typo in API? Plugin might depend on that name.
  • Order of events on subsystem? Plugin might depend on the order.
  • Third party dependency version? Plugin might depend on it.
  • Python 3 compatibility? Plugin might not be Python 3 ready.
  • ➡ Have to think of consequences all the time


  • Need to be very careful with every single change
  • Breaking backwards compatibility = breaking established plugins
  • Breaking established plugins = unhappy users 😕
  • Sometimes means bending over backwards to solve a trivial issue

Please be patient if a seemingly trivial change appears to take ages 🙂

Challenge #4

Supporting the masses

Consumer mentality vs DIY enthusiasts

  • Early days: Huge overlap between owners & DIY enthusiasts
    • Tinker happy
    • Happy to google around for a solution
    • Capable of fixing stuff themselves
  • These days: Lots and lots of consumers
    • Printers are marketed as plug-n-play but aren't
    • Many owners never had to tinker before
    • OctoPrint might be their first interaction w/ Open Source


  • Lots of development/OSS inexperienced users
    • Constant need to ask for logs & more info that "it doesn't work"
    • Tricky to explain some things, e.g. why proprietary printer won't work
      and can't "quickly be added"
  • Sometimes expectation to get support on par with huge multinational company
  • Sometimes hostile reaction when told inconvenient truths


  • Huge support overhead
    • Hours per week of fielding questions
    • Repetitive
  • Often very frustrating experience
  • ➡ Established community forum
    • Central place for support, questions, sharing
    • Not just me anymore, everyone can help to help
    • Seems to work best so far

Please help each other with questions and problems 🙂

Challenge #5


This has become a job

  • Project size way way past pet project level:
    • Maintenance
    • New development
    • Community management
    • Support
    • etc
  • Full time job and then some
    A lot of people think I'm a multi person company 😋


  • Turned part time in 2013 (own cost)
  • Turned full time in 2014 (single sponsor)
  • Turned crowdfunded via Patreon in April 2016
  • It works 😲
    but is also really scary
  • Huge thanks to the community! 😍

If you like OctoPrint, consider supporting my work on it 🤗





Thanks for your attention!