I’m seeing something strange. I think I know what’s going on, but I want to hear from the experts.

I used Affinity Designer to create a four color logo and separate it into four .svg files, one for each color.

I import these four .svg files into OpenSCAD color and extrude them all the same height then create a union and translate up by the height of the base (see below). This is the top, colored layers of my object.

I do the same import with a different height and change the color of the entire union to the background color. This is the base of my logo object.

I then export the union of these two as a .3mf file into my slicer (Bambu Studio).

When I slice the object, inside the base portion which should be a solid color, I see inclusions. I don’t see any relationship between these inclusions and items in my .svg files. I’ve examined the .svg files and don’t see anything in there, although I could be missing something. The inclusions appear differently on different layers, so if it were an error in the ,svg file, I would think the inclusion would be at the same location on every layer.

If I do a hull on the base object, the inclusions go away.

Is this a rendering issue where rounding causes small gaps between the separate color .svg curves or something else.

Mark

Your theory that there are micro gaps between the SVG images certainly
seems plausible.  Exactly where in the pipeline they might have come
from ... who knows.

It's not terribly surprising that they would vary from layer to layer,
because the Z component of the extrusion is triangles connecting points
on the bottom to points on the top, and those are not going to be
straight lines.

Given the data files we could look closer.  My first step would be to
take the SVGs, import them all into Inkscape, and look at them with a
microscope.

There looks to be ~0.002mm of gap in the first region I checked:

William

I did some more checking and I think I may have found the issue. Was the file you found the gap in black.svg?  That file has text that was generated in Affinity Designer. The other three (red, white, blue) were all drawing.  Affinity Designer has an option to fill holes. I went into black.svg and made sure the letters were converted to curves and then did a fill holes on those curves. It seems like that has cleared things up.

I’ve attached an archive with the updated black.svg and an updated OpenScad file (removing the hull()) and when I import the output into Bambu Slicer is doesn’t appear to have the inclusions.

Thanks again for looking into this.

Mark

I wasn't able (in a few minutes) to figure out how to load multiple SVGs
into Inkscape and preserve their positioning; it wanted to center each
of the individually or something like that.

But I looked at your OpenSCAD model closely, looking only at one
invocation of shield(), and if you look really closely you see a very
small gap between the colors, at least for curved boundaries.  Exactly
where that gap comes from, I don't know.

Tidbit:  you didn't have to split it into three SVGs.  If you have an
SVG with multiple layers, you can use the "layer" parameter to import()
to cherry-pick a particular layer.  Or, at a finer level, you can use
the "id" parameter to cherry-pick particular objects.