Picture Above: Clyde, Atomic, and Ronin (cliché for a samurai betta, I know). Photo Credit: Hannah Carter, 2026

Following Tom's Hardware guide as I have 3D Printed before, it just has been a while, and I have not performed this on FreeCAD.

Discoveries:
You do very much need to be running the command line as an admin to complete installs from a GitHUB when modifying your FreeCAD set-up.
And of course the obligatory "nothing can go right the first time" the init files downloaded displayed an error preventing the 3D Print function from being added to the Workbench. Upon closer inspection, not all Python indents are the same. Error was correct by copying and pasting the indents in the source code (python source code) and correcting the issue.

Error Log with error "During initialization the error "inconsistent use of tabs and spaces in indentation (<string>, line 52)" occurred in" "X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\InitGui.py Please look into the log file for further information".

Source Code from: https://github.com/cblt2l/FreeCAD-CuraEngine-Plugin

Code Prior to Fix

Fix

Final correct implementation listed below with init files implementing correctly.

Menu Option "3D Printing" for slicer present.

Moving on, time to start 3D Printing the Betta raft prototype.

And it is never that simple. New error message:

"Running the Python command 'sliceCuraEngine' failed:
Traceback (most recent call last):

File "X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\Commands.py", line 61, in Activated import SlicerPanel

File "X:\Program Files\FreeCAD 0.20\bin\Lib\site-packages\shiboken2\files.dir\shibokensupport\__feature__.py", line 142, in _import return original_import(name, *args, **kwargs)

Missing parentheses in call to 'print'. Did you mean print("chooseOutputDir")? (SlicerPanel.py, line 198)Save AutoRecovery file: Needed time: 0ms"

As been said by many an engineer:
32 bugs in the code on the wall
32 bugs in the code
Take one down
Patch it around
157 bugs in the code on the wall.

Patched the bug in line 198. Patch created more bugs. Reverting fix and investigating further.
Below: Original code

The fix

Reverting code..... Nevermind, unreverted code.

When you open the 3D Printing workbench before the part, you receive different errors.

Error Panel:

"Running the Python command 'sliceCuraEngine' failed:

Traceback (most recent call last):

File "X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\Commands.py", line 61, in Activated

import SlicerPanel

File "X:\Program Files\FreeCAD 0.20\bin\Lib\site-packages\shiboken2\files.dir\shibokensupport\__feature__.py", line 142, in _import

return original_import(name, *args, **kwargs)

EOL while scanning string literal (SlicerPanel.py, line 198)"

So stepping back through from the beginning, clicked the "Define a 3D Printer" Button and received a large amount of errors:

":\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:104: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "string":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:106: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "float":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:112: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "string":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:114: SyntaxWarning: "is" with a literal. Did you mean "=="?

elif pt is "float":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:120: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "string":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:122: SyntaxWarning: "is" with a literal. Did you mean "=="?

elif pt is "float":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:129: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "string":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:131: SyntaxWarning: "is" with a literal. Did you mean "=="?

elif pt is "float":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:137: SyntaxWarning: "is" with a literal. Did you mean "=="?

if pt is "string":"

"X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\SliceVars.py:139: SyntaxWarning: "is" with a literal. Did you mean "=="?

elif pt is "float":"

"Running the Python command 'createMachineDef' failed:

Traceback (most recent call last):

File "X:\Program Files\FreeCAD 0.20\Mod\FreeCAD-CuraEngine-Plugin\Commands.py", line 50, in Activated

reload(MachineDef)
name 'reload' is not definedSave AutoRecovery file: Needed time: 5ms"

"Save AutoRecovery file: Needed time: 0ms"

"Save AutoRecovery file: Needed time: 0ms"

Switched my visibility settings (my eyes didn't know how much they hurt on the previous setting, whoopsies).

Photo Credit: Hannah Carter, 2026