Minimal AAA battery mount(s).
I found and tried a lot of other mounts but they were all too big for my electronics projects.
This is created to take up a minimal amount of space, retaining the necessary sturdiness.
Add copper wiring using the holes to create your circuit.
If you want, you can glue this into your existing creations, or use the files as a basis for new projects.
The model in Blender