Insulators

Insulators
making the insulating preforms

As shown below, the biggest issue with assembling the pack safely with charged batteries is keeping all the junctions between cells separated until they can be properly supported. The shaped heat shrink seems to do the job, so I made a new inner form out of pine to make a bunch of the insulators.
The remaining shrink had a lot to do with how distorted the rectangular shape got when the final shrink took place. It seems that using a larger shrink tube using most of the shrink to achieve the preform was much better than only shrinking a small amount to achieve the preform, so I used the larger white shrink.