After attempting to make do with too-big inherited thimbles, I finally have one that fits. 13 mm was harder to find than medium sizes, so I bought online. (For anyone else in need of a small tailor’s thimble, there’s also an Osborne #5 that’s 13 mm. I haven’t seen smaller.)
I liked this so much I made a video for it. It’s easy and only requires a double eye needle and a machine with a zigzag stitch. These needles used to be popular and were sold as “magic” or “basting” needles. Now Schmetz is making them again to market them for decorative stitches. (I’ve gotten them cheaply on ebay here.) You can do regular sewing by threading the bottom eye and basting by threading the top eye and following the steps in the video.
ETA – As pointed out to me by a member of the Bernina Lovers fb group, you can baste with an even longer stitch using the blindhem stitch.