Starlight:
I wish there were holders. I had to have battery packs made.
First, the batteries were glued together.
Second, copper strips were soldered across two batteries at each end to create the 3-cell series.
Third, the copper strips were covered with tape.
Fourth, the pack was shrink wrapped (except for the ends)
Fifth, the remaining opposite end positive and negative contacts each had a convex curved copper stip soldered to stretch across the center of the end for device contact.
Sixth, a nipple was soldered onto the center of the positive end copper strip.