How would i go about making a door, triggered by putting 3 batteries in holsters?

In HL2 there a door that requires you to put 3 batteries that are randomly scattered around in holsters to power it, so that i can open.

I’ve also seen it done in ZM, in zm_gasdump.

How would i do it?

There you go:

Thankyou Bird Poo :slight_smile: