There are a few more of us really, really want to know too!
They are good pieces, well-made, interesting and I believe they have some (small) age, although I don't know how much, I would think the "retro" sort of implied era.
Your query though, has added you to the list of us who have found these, liked them and been curious enough to buy them in the hope that an attribution might be found some day.

We don't give up here on the gmb. Some attributions happen in minutes, some take years.
This is one that has been ongoing for years. It's stuck in some of our heads, we're always on the lookout for an id and when it happens, it will be announced here.
