One cannot (or, perhaps, should not attempt to) solder parts to 14 AWG wires seated in a 3D printed battery holder base, so I cleaned up the edges of two polycarbonate scraps:
Then drilled holes to match the strut positions:
The holes fit snippets of the original wire insulation, because, after all, polycarbonate is a thermoplastic, too.
Stretch some copper wire to straighten and work-harden it, add insulation snippets, then maneuver everything in place:
I definitely need a third (and maybe a fourth) hand to hold each part, the solder, and the iron, but at least the wires won’t walk away in the middle of the process.