Hi, that’s a tenting case that does come with stainless steel M5 bolts and nuts that you can adjust to your height preference. I do sell them here: https://kriscables.com/product/lily58-pro-acrylic-tenting-case-kit/
I have cut the acrylic to exact size of 1000mAh battery. Probably i would recommend to position the battery where i have cut my logo in the middle of the base for 2 reasons:
Just my personal notes and suggestion, but this way it works for me
Supermini NRF52840