Those mirror caps/covers come from Monaco Motorsport. They have a page and a half of model 3 exterior bits. I've mostly seen this style of mirror cap on BMW.
Our mirrors don't want to fold in all the way with these on.
They took 3 and a half weeks to get here (slow boat from china)
They cost way way too much at $160 for black abs(plastic), I see they are now on sale at $135
The fitment gaps are too much, way worse than stock, but no one will notice, it's all black and shadowy there.
With all that said, I think they look cool.