I went a different route... I used hard o-rings as spacers on the 5 that shipped yesterday and squeezed them to fit correctly.
Since the one on the door was broken when it arrived, spacers wouldn't help.
Might help with the smaller R422CS magnets though?
The R622CS pair has enough pull (got bit putting the door on the first time with them) that the only rattle on mine is the firing button.
I don't see any issues with the minor fit issue of the bottle, though a small tweak would only make it better.
But I do wonder where the odd size came from.
Metric I assume, 7 or 8mm? I never measured it in mm.
Oh, pretty sure the contacts were custom built, not of the shelf.
He farmed out all the manufacturing. He just assembled the parts he had made. Should be hard to make on though. I wouldn't bother with the roll on the batter end. I'd solder a button on the end like some other mech mods do.