Bad design files will throw errors and create models that explode or cannot be solved, here are some tips for
importing FOLD or svg files that work.
The FOLD file format is specified in these docs.
This tool imports FOLD v1.0 files with all of the following fields populated:
If you are unsure whether your FOLD file is valid, you can inspect it using the
The SVG importer supports path objects and line objects (coming). Please convert polygons to paths before importing.
Valley folds are red - rgb(255, 0, 0), hex #ff0000
Mountain folds are blue - rgb(0, 0, 255), hex #0000ff
Outline edges are black - rgb(0, 0, 0), hex #000000
This tool will automatically triangulate regions in the pattern that form polygons with more than three sides.
To control the triangulations draw lines in yellow - rgb(255, 255, 0), hex #ffff00
Stroke and line style do not matter.
The final fold angle of a mountain or valley fold is set by its opacity. For example, 1.0 = 180°
(fully folded), 0.5 = 90°, 0 = 0° (flat).
This tool should be able to automatically clean files of slightly misaligned vertices, stray vertices,
duplicate lines (coming), and extra vertices falling in the middle of an edge (coming),
but it is recommended to remove these errors yourself in order to avoid problems.
If your simulation is not working, check that the pattern looks correct by clicking on the "Pattern" view in the top nav bar.
For Adobe Illustrator users:
I use Illustrator to create SVGs (though any vector editing program should be fine), here are some tips I've found for making svgs to import into this tool.
If you are starting with a pre-made vector file, first ungroup any groups, release all compound paths
(Select all + Object>Compound Path>Release), and release all clipping masks (Select all + Object>Clipping Mask>Release).
Create geometry using the Line Segment Tool.
Illustrator can help you select all lines of a particular type so that you can edit their color or opacity together. Click the line,
then go to Select>Same>Appearance to select all similar lines in the pattern.
To turn lines and polygons into path objects, select the geometry then right click and select Make Compound Path.
Finally hit Save As and select .svg extension. I'm using the default SVG Tiny 1.1 settings, but I believe versions 1.0 and 1.1 will work.
Dimensions: (the STL file format is unitless, but typically assumed to be either in inches or mm)
Dimensions: For more information about the FOLD file format, see the offical docs.
"Average node error" gives a sense of how much the distance constraints in the
origami pattern are being violated. The error at each node is evaluated by averaging the
percent deviation of all its distance constraints with adjacent nodes. This error is
reported as a percent of the total length of the distance constraint to remove scaling effects.
This measurement is equivalent to
Cauchy strain or engineering strain of the axial constraints on this system.
Increasing the "Axial Stiffness" will tighten these constraints and
lower the error in the simulation.
To visualize the error of each node graphically, select "Axial Strain Visualization" under "Mesh Material"
in the left menu.