is there a way to choose which components will be sported to STEP file? Chicken-food parts (smd passives, small discretes, etc) are largely irrelevant to mechanical integration of the PCB, but increase STEP file size and complexity quite substantially, which lowers (often quite significantly) 3D CAD performance.
Is there a way to export only selected parts, or for example omit parts with certain footprints? Can this be accessed via a script?
the only way I can think of is by adding a variant named something like "STEP export" where components not to be plotted are "not fitted".
Or, if you don't have a STEP model assigned to your footprints and just want to avoid the export to the automatically generated "3D view", you can do this: Lets say your resistor footprints are named something like "RES0603", "RES0402" and so on. You can add a 3D view named "RES*" to your 3D view library. In the 3D package editor choose "package style" "user" and just don't define a package. Now no resistors are plotted in 3D view or STEP export. At least that is what i did to avoid 3D data generation for my fiducials. Maybe there is a more elegant way to do this.
The most obvious way is to have a number of different folders where you keep your STEP files and put all the chip passives in one of these separate folders then enable/disable folders at will. This gives you the advantage of keeping the STEP model information in the design and turning it on or off at will. Pulsonix will substitue a shape of the <Component Height> attribute where there are missing step models.
You can also use EDIT ATTRIBUTES in the PCB Design and overwright the contents of the <STEP Filename> attribute for components, deleting them so that they are blank, however you would have to RESET them to bring the information back.
In one of the latest builds [Pulsonix 10.5 build 7879] there is also a Minimise STEP file size radio button that can be selected. You can find it by pressing 3D Settings in the Output STEP dialogue and clicking the Output tab in the dialogue window that opens.
You didn't mention how you are obtaining your step models for your passive components.
If you are using PCB Library Expert from PCB Libraries this program lets you output either a nice High Quality and larger file sized STEP model or a Low Quality and smaller file sized STEP model. You could also try changing the STEP file version from AP214 to AP203 if you are only bothered about mechanical fitting and not having nice colours to view on screen and perhaps use in presentations or assembly work instructions.
You could also use FREECAD to create your own STEP models that are just basic rectangles which will end up small in file size then the ones PCB Library Expert outputs.
If you wanted the extra work you could set up different folders for different types of STEP file outputs keeping the same name for the STEP file of a specific component in each folder, then enable and disable the folders at will.
STEP Models PCB Libraries High Quality/ STEP Models PCB Libraries Low Quality/ STEP Models Very Basic Shapes/
And have different versions of the RESC320X160X140L50.stp file in each folder, that your footprint RESC320X160X140L50N has for <STEP Filename> in your library.