This is an interface between the RIDGID 18V battery line and the older-style Hitachi Koki 18V NiCd power tools.
I remixed others' designs. I re-used the part of the Hitachi NiCd battery case that goes into the tool (top part). It bolts on the printed interface with 4-40 socket head screws.
The adapter has two parts that are superglued together, the electrical connection housing and the adapter proper. For the electrical connection hardware, I turned two small brass posts and silver soldered them on the brass springs I got from a regular female connector. It is sturdy and works a charm. Others have done it better.
I used supports and it came together well.
I used 7 wall, top, bottom layers.