[Doohickey-d]

This seems like a cool design!

One question though: it seems like the contact between the PCB side panels and the cells relies on flexing the (FR4?) PCB material of the small per-cell "fingers" that are surrounded by cutouts, on the side panels. I wonder if once it's in this "flexed state", it will eventually fatigue, or settle into the bent state, after some time (years?), and no longer press on the cell ends strongly enough?

A bit like if you were to leave a rubber band in stretched state for a while, it won't fully go back to the diameter it was before.