Hello Johanna.
I would use the region feature in the shadow area and let KeyShot res up for a while. So in the heads up display you would see, when or at wich sample rate no artefacts were visible. I guess also the de-noisier would do a pretty good job. And on top, you can change the material type to plastic transparent or advanced, so you can change the material samples from the gloss parameter.
What’s the reason to use interior mode instead of product mode?
If you search for interior renderings and artefacts in this forum, you’ll find a lot of examples with similar issues and the solutions as well.
Hope that helps.
CheerEO
Marco
