So, I was strolling through Amazon when I came across this gem.
A third party seems to be selling replacement earcups for the q20. For me it is the first time that I saw a replacement for a Soundcore item. I hope that this is a trend as earcups are usually one of the items to wear out on headsets.
We were running a thread, were we discussed that.
Without that plastic part its nearly impossible to do a fitting satisfying replacement.
For me, this kind of special earcups are a design fault of the soundcore headsets.
Could be done much more customer friendly.
But these are not available as far I see,
There are such ones for the Q10 (But can not be bought here 
)
Quite expensive!
eg. refurbished headphones cost only the double.