I have a bunch of AG13 batteries left over from when the kids were into hex bugs. I have a bunch of LED’s.
I 3D printed some AG13 battery holders, enough for two batteries. I slid the LED legs between the batteries and the plastic case. Result, we saw the light.
Some of the cases with AG13 batteries and LED’s in them.
This was printed on a Tronxy X1 printer with PLA+.
One of the cases, naked.
Here is the design on tinkercad.
This design would benefit from a flatter bottom so that they don’t topple over, and higher sides so that they hold the batteries better.