dalbert,
Thanks for the suggestions. I will consider a schottky separated AA(A) battery power.
That means the CR wont charge the batteries, and you have to supply enough voltage to stay above 3.3V+LDO-dropout ~3.5V.
If I implement that in a future CR, I can post a deeper box for folks to print if they prefer AA(A)s.
But the default will stay as is for now, each case already takes around 50 minutes to print ;-)
Thanks Tom for answering the other question!
FWIW the CR power/battery use/guide page is
posted here.