Yea, that's actually a great point!

I glossed over that pre-CAD prototyping in the post since we built those first "duct-tape prototypes" a long, long time ago. So we don't have pictures readily accessible and it was harder to remember the exact process.

To start with, I think we modified another battery case and basically stuck batteries on the back to try out swapping.

I'll think about how to incorporate that step into the post and see if I can dig up some old photos.