Budget waterproof 1S2P light?

I only want to use it as a battery box so don't really care about optics or electronics, just need it to be 1S2P and waterproof do you know any light answering this spec?

Few options from parametrek search

Personally, I just use one of my soda can lights as battery carriers. D18 or SP36 for protected. I just make sure I don’t mix empty and full cells if I want to use them as lights.

Unfortunately most of these lights are 2S1P and none of them is budget (at least not just for using as battery box)

Sorry for not being so clear, I want to use it as a battery case for a headlamp, not for carrying batteries.

You might search for bicycle light battery packs, there’s quite a variety of those out there.