So from Green Batteries http://www.greenbatteries.com/battery-adapter.html
I had purchased 4 sets of their battery Adapter/Size Converter Kits that convert AA & AAA to C & D size.
Mainly to convert some AAA's to AA's.
So I have several sets of the C and D adapters that are not being used.
I had purchased some cheap LED flashlights at a "dollar Store" for the triple LED lights for another project.
So I had these AAA battery holders that weren't being used.
2 batteries are inserted in the same direction and 1 battery is inserted in the opposite direction.
I realized that those battery holders would fit in the D size adapters with a little modification.
So I soldered the terminals on both ends of the battery holder to make contact with all 3 post in the same polarity .
Then soldered and filed down a small tip on the "+" end of the holder to make contact with the "+" in the D adapter.
Then inserted the 3 AAA batteries into the holder in the same polarity/direction.
Then placed the AAA holders in the D adapters.
So now I can power a few "D" size gadgets with my excess of AAA's.