I bought an enclosure from ORICO a couple of weeks ago, and be very happy with it so far.
I couldn’t found the one I have on the US-AMZ, so I don’t share a link here, but while I was searching for the right one for me, I learned that there are sometimes big differences between the enclosures regarding the effectiveness of the cooling.
If you have an enclosure, you want to buy, I would recommend to try to find some tests or at least blog posts about it, to see, if the (passive) cooling is working on that one.
And be careful, if there is a kind of a patch in the box, high chances that this might be a kind of a cooling gel/transfer gel that belongs between SSD and enclosure, to distribute the heat to the outside.
This guy makes the same point and the need to have good cooling without which the speeds can get throttled. His recommendation is also an ORICO case. I see that some cases also come with a foam like piece to transfer the heat.
DIY seems to be the way to go. And strong performance for thunderbolt, as you’ve mentioned in an earlier post!