Look for my other keyboard designs at https://thumbsupkeyboards.etsy.com/

This adapter allows using the soft rim caps from the old Thinkpads with the newer models.

The new Thinkpad x280 came with a new touchstick style - the stem is smaller (2.x mm vs. 4.2 mm in the old ones).

Lenovo in its infinite wisdom does not make the soft rim caps for that stem size. From now on - soft domes is the only available style, which are highly uncomfortable and IMO are the main reason people hate the touchsticks in general. Neither Lenovo sells adapters for the new stems. (Remember the old IBM days when each ThinkPad came with an assortment of the caps, eh!)

(Well, I found that the old x200 also did have such thin stem too, and it was using an adapter. But the keys in the old model were also higher, so the old adapter does not solve the problem completely.)

Thanks to @petolone for the idea. I somewhat improved it - instead of a square hole I made the inner tube. This way it comes out of my printer much better. The hole still needs drilling - I used 1/8" bit and switched the drill into the counter-clock rotation mode (as if unscrew a bolt). This way it not cut but rather softened the material and widened it just a bit.

Insert the printed adapter into the cap firmly, then snip off all the extra rubber.