A collection of small AA battery boxes. Inside the floor of each battery compartment there are alternated polarity indicators, the end connections provide a grip to make good contact and hold the battery in place.

UPDATE: Added 5 and 6 cell designs.

Doesn't Matter

No

.2

35

I used a higher infill for strong thin walls. Probably not necessary.

I used 1/8" adhesive copper foil to link the batteries and 28 gauge wire for output.