I have a stack of old 18650 cells building up from old laptop battery packs and needed a way to charge them. A quick scour of eBay and I sourced some of those lovely USB 1S chargers.
Awesome.

Fast forward 6-8 months and now, being in possession of a 3D printer, I am able to charge the darned things and press those Chinese chargers into good use (they're great BTW)!

A quick scan of the wonder that is 'Thingiverse' turned up a plethora of options, and they were all stored away in one of my growing collections.

This morning (or at least it was when I wrote this) I printed this little beast - https://www.thingiverse.com/thing:2847497 - it's great, the self contained spring mechanism is faultless and the battery fits like a dream . . . . . . unfortunately my little Micro USB 1S PCB does not (different dimensions and indeed shape).

Another dig into my collection turned up one with the EXACT PCB I have (phew) - https://www.thingiverse.com/thing:2847606

This one has the correct PCB holder but I'm not as keen on the whole 'use a bolt as a contact' thing, especially as some of my cells are different lengths (some are protected, some not, you know the drill).

So, into Fusion360 they both go, hack the PCB holder off both, graft the 'Franken-Parts' together, fiddle a wee bit to match (sorta) the differing dimensions and voila - there we go!

It works for me, it may work for you, and it might already have been done - thus rendering all my effort wasted.

Ho hum, it's all practice!

Enjoy.