Yeah, you can get a Thunderbolt enclosure (Jeyi on Aliexpress seems to be very good) and a fast SSD and it will work almost as fast as your internal SSD. It works out only slightly more than a fast external SSD like the Kingston XS2000 or the Sandisk Extreme Pro. It will be faster. But I doubt you'll notice, because apps and OS will be on the internal one. So I'm going to save myself the hassle and I will get a commercial drive if ever I need more storage.Presumably a fast external SSD via Thunderbolt is going to be pretty damn quick? Assuming all the OS stuff lives on the internal SSD etc.