There are some Openscad models for 8020.net parts.
There are design files available for from the 8020.net website, but nothing directly available for Openscad. For just the aluminum extrusions, you can download the 2D DXF profiles (see this imgur post for example). however, it appears that not all the DXF files import correctly (for example, I was unable to get the 8016 profile to work with Openscad. For those that did work, I sometimes had trouble exporting it into STL files that worked with Freecad or SolidWorks.
But besides these problems, there are no models that I could find for some of the other 8020 parts. The natural thing to do was of course to just roll my own.
The aluminum extrusions are based the DXF files; the other parts are based on the drawings and descriptions from the 8020 catalogs. I have tried to make these as accurate as possible, according to my understanding of the parts. But there may be errors, so use at your own risk!
The ".scad" files should be placed in the Openscad library path, in a 8020 folder. For Linux, this would be in
$HOME/.local/share/OpenSCAD/libraries/8020/
A full rendering of the exact profile of the extrusions and details of the parts can be time consuming as your models become more complicated. For many applications, this is not necessary, especially in the initial design stage. The models in these files will look at the variable G8020FAKE; if this variable is set to "false", the fake/mock-up pieces will be used instead the detailed models.
openscad -D G8020FAKE=true mymodel.scad
(see images below). This allows you to finish your design with the mock-up parts, and later switch over to full details for rendering later.
In addtion, if you only care about the exterior of the extrusions, and don't ever need to look at the interior cut-outs (particularly if you are covering the ends of the extrusions anyway), then you can set the variable G8020OUTERONLY to "true" to skip over the interior details:
openscad -D G8020OUTERONLY=true mymodel.scad
(see images below).
(last revised 2020-12-20)