Hi,
I designed an Box which fits the Battery-Boxes of those LED-String-Lights.
My box measurements are inside: 38mm (width) x 71.5mm (height) x 23mm (depth) and fits those String Light Boxes with 2 AA Batteries.
The Top needs to be puttet on the box without force, it fits really great :)
It can be taped, or screwed (there is a hole on the back) onto a wall :)